For a real professional text editor to edit a 200-page manuscript for $100 is an act of charity, no matter where the proceeds go. That price is far too low.
CityMouse, $1000 to copy edit your manuscript might be a fair price, or it might be a ripoff, depending on the copy editor who charges it. Could you tell us more about his professional qualifications? If he's an honest freelancer, those can hardly be confidential.
Some useful questions to try on people who claim to be copy editors:
1. What's your opinion on the serial comma?
They should have an opinion. It should be firm. If it doesn't match yours, start arguing about it now.
If they say "Serial comma?", say "Oxford comma." If they still don't know what you're talking about, they aren't text editors, period.
2. Just speaking personally, what's your preferred working dictionary?
If they just say "Webster's", they're faking it. No publisher owns the rights to that name, so there are any number of "Webster's" dictionaries out there, some of which would be improved by being shredded and used as compost.
If they say "the OED," you should also be alarmed. The OED is an invaluable reference, but it's not an everyday working dictionary.
If they say "whatever dictionary you prefer," they're either a cynical old text-ronin (unlikely), they're being over-deferential for some reason, or they're faking it. Copy editors always have preferences in dictionaries, and they almost always distrust the client's taste in same.
Real copy editors are prone to say things like "I prefer the Concise Oxford, but then I'm British. I assume you'll want me to use American style?" Or: "I know everyone's using Webster's 11th New Collegiate, but I personally prefer the 9th New Collegiate." Or: "Webster's Third Unabridg -- no, sorry, New World College Fourth."
3. Do you have a preferred stylebook?
"I use Strunk & White." Translation: "I am a lightweight. An amateur. An English major who reads a lot. I don't know what a stylebook is for. I may not be aware that copy editing is a separate and specialized professional skill."
"I use the Merriam-Webster Manual for Writers and Editors." Translation: "I am content to use a dumbed-down version of the Chicago Manual of Style."
"I use the AP Stylebook." Translation: "I am a journalist, tech writer, or other unspecified nonfiction writer. As such, I have real strengths; but the conventions of copy editing fiction may be completely unknown to me. I am also prone to believe that there is such a thing as standard style. If so, and if I'm feeling motivated, I can completely flatten variations in characters' voices in dialogue; go through the narrative and regularize what had previously been carefully contrived elisions, ambiguities, inversions, and other non-journalistic constructions; and substitute common present-day locutions for your historical/SF or fantasy/other specialized phrasing and terminology."
(Note: Renegade tech writers and nonfiction copy editors have a long history of doing dreadful things to novels and personal memoirs. However, there's always a chance that you've gotten hold of one of those middling-rare switch hitters who are good at both fiction and nonfiction copy editing. Talk to your prospective copy editor. Ask them about their background. If they've done any work on fiction, find out what kind, and if possible the level at which it was written. It takes no judgement to bash awkward sentence structures and correct near-homophone errors in badly written books. What you're looking for is thoughtful, sensitive work done on manuscripts whose authors can fight back.)
(And find out what they've read. Unless you're writing strictly modern mainstream, in the current version of transparent style, you want them to at minimum have read works published earlier than Thomas Hardy's. This goes double if you're writing historical fiction, science fiction, or fantasy.)
"I have a Microsoft Manual of Style; will that do?" Translation: "I am a tech writer from the computer industry. Bug: I've never worked on fiction or in trade publishing. Bug: The author gets a say in things? That's a new one. Bug: I can't believe how little copy editors get paid. Feature: You can't scare me."
"I prefer the U.S. News & World Report Stylebook." Translation: "My background is in nonfiction and/or journalism, with all the problems that implies (see above); but I learned copy editing from a sterner taskmaster than that guy who uses the AP Stylebook."
"Sure -- I use the U.S. Government Printing Office Style Manual. It's got everything." Translation: "I have internalized an idiosyncratic set of quirks, crotchets, and rules not encountered elsewhere in the English-speaking world."
"I use the Oxford Guide to Style/the Oxford Style Manual." Translation: "I am British, or wish I were."
"The Times Style and Usage Guide." Translation: "I am a British journalist. Please buy me a drink."
"I use Hart's Rules." Translation: "My underwear is made of heavy wool tweed."
"I've always used the MLA Style Manual." Translation: "I am a renegade academic, and may or may not be native to your planet."
"Is Wired Style okay?" Translation: "I am in a humorous mood, and am pulling your leg." Other possible translation: "I have never worked on a hardcopy publication. I was brought here from 1997 by a malfunctioning time portal. Do you suppose my stock options are still worth anything?"
"I like Words into Type." Three possible translations: (1.) "Yeah, I know a a lot of people are going over to Chicago these days, but I've been using Words into Type for over twenty years now, and I'm comfortable with it." (2.) "I'm not normally a copy editor, and I don't consult a stylebook more than once or twice a year, but we used Words into Type on my college yearbook, and there was an old copy of it kicking around the offices when I got here, so that's the one I use." (3.) "I have the following highly technical disputes with the underlying theory and overall sensibility of Chicago, and furthermore I loathe the latest revision of it, and anyway who needs to look up all those rules and exceptions when I can just remember them on my own and use the ones I agree with?" (Note: #3 will have a frighteningly long attention span. If you wind up drinking with her, don't ask her about her disagreements with Chicago.)
"H. W. Fowler's A Dictionary of Modern English Usage." Two translations: (1.) "I am confused, and think you're still asking about personally preferred reference works." (They don't use him as an everyday working reference, but the tribe of English-language geeks and mavens has a persistent fondness for the first and second editions of Fowler.) (2.) "I am a language-besotted weirdo. Please introduce me to that ravishing female who was ranting about her disagreements with Chicago."
"I use the New York Times Manual of Style and Usage." Four possible translations, some of which may overlap: (1.) "My background is in periodicals, not books." (2.) "I didn't learn copy editing from other copy editors, or at least not from book copy editors." (3.) "I can't stand having to wade through all that extraneous material. Just give me the answer as quickly as possible." (4.) "The store had several stylebooks. This one was the cheapest."
"I use the Chicago Manual of Style." Two possible translations: (1.) "I am a professional copy editor, and Chicago is predominant usage." (2.) "I am aware that Chicago is the current default option, and have claimed to be using it. This tells you next to nothing about me. Maybe I'm a real pro. Maybe I took a superficial continuing ed. class in copy editing, and the teacher required me to buy a copy of Chicago, but I'm still not sure how to use it. Maybe I'm a self-taught copy editor and I believe everything Chicago tells me. This may not scare you, but it should. Maybe I asked the sales clerk at Barnes & Noble which stylebook is currently popular, and she told me Chicago, but I haven't actually bought a copy. Et cetera. All you can tell about me is that I know to say, 'I use the Chicago Manual of Style.'"
(And a historical note: Words into Type and Chicago used to be equally preferred standard options for American trade fiction copy editing. Chicago has overtaken Words into Type, but the latter is still a respectable professional choice.)
4. What do you count as privileged forms of speech?
You're primarily asking this question to see whether they recognize the concept. Discussing the extent to which this or that kind of speech is privileged comes a distant second.
Privileged forms of speech include dialogue, internal monologue, and first-person narrative; excerpts from letters, books, poems, or other extant texts; signage and inscriptions; poetry; quotations; prayers and liturgies; and the main narrative itself, if it's strongly voiced. They're the set of all varieties of speech a copy editor is not allowed to re-render into standard English.
Someone who's unfamiliar with this set of practices has not worked as a trade fiction or nonfiction copy editor.
5. How many passes do you normally do?
The question is, how many times do they read through the manuscript on a word-by-word basis, making notes and correcting errors? The copy editor's base fee should cover at least two full passes.
You don't know what the language in a book is doing until you've read it, which means you can't do it justice in a single pass. Without that second pass, you can't fix or query early continuity errors, or recognize and correct early instances of persistent inconsistencies. Also, there's a rule called "predominant usage" that says that if a name is spelled one way three times and a different way 91 times, the latter is correct. If you just make a single pass, and the three incorrect instances come first (which they often do), all you can do is correct the subsequent 91 instances to match them, which will be wrong.
I've seen copy editors who claimed they could do a good job on a book in a single pass. They were wrong. I've also seen copy editors argue that if they have to make two passes, they can't make a living wage. They have my sympathy, but they need to find another line of work. Two passes, minimum.
6. What's your overall take on copyeditorial latitude?
They should have several sentences' worth of opinions on this, at minimum. This is another question where the specific answer is less important than the fact that they recognize the question and the issues it raises.
Copyeditorial latitude is the extent to which the copy editor is allowed to make changes, and the reasons he or she is allowed to make them. If all they're doing is checking for obvious grammatical errors and misspellings, you're not getting your money's worth.
Every novel redefines the language in which it is written for the duration of that book. One of the signs of a good copy editor is that they can distinguish between errors and bad usage, on the one hand; and on the other, quirks of language that are characteristic of the book. Consider a single pair of words which is arguably a compound adjective. Should it be hyphenated? Good question. Some pairs have to be hyphenated: blue-green algae, fish-shaped jello mold. Others aren't so clear. What to do?
The thumbfingered answer is to go to your dictionary of choice and see whether that pair of words is listed as a hyphenated form, or perhaps as a single word with no hyphen. Depending on which dictionary you get hold of, you might be told that blood red, as in blood red roses, isn't blood-red, but rather bloodred: an uncouth word that's obviously pronounced BLUE-dread, and is guaranteed to make the reader stumble.
Bah! Copy editors who insist on dictionary usage drive authors crazy. Even worse are the copy editors who think that the first-listed or preferred form of a word is somehow the only correct version of it. Listing hijinks or genie first doesn't mean hijinx or djinni are objectively wrong. It just means they're the less-common spellings of the words; and in the context of this book, they may be exactly the right spellings.
Let's go back to that pair of words that's arguably a compound adjective. Again: do you hyphenate them? Here's the good answer: Some authors go light on hyphens. When there's an edge case, they leave it unhyphenated, and trust that the readers can sort out which word modifies which. Other authors are heavy on hyphens. When there's an edge case, they hyphenate it. They may even use en-dashes to distinguish the connection between a single word and an existing compound adjective that are being yoked together into a new adjective: pudding-bowl--shaped.
The answer to whether our arguable case should be hyphenated is that it should be handled in whatever way is least likely to confuse the reader. If the author uses a lot of hyphens, not having one linking that pair of words could read as an unnecessary ambiguity. If the author's light on hyphens, putting in a hyphen could read as an undesirably emphatic reification. It all depends on what the author is doing with language in this book.
7. In your view, what else does a copyeditor do?
For the record, he or she should compile lists of proper names, place names, easily misspelled words, new coinage, odd usage, symbols and other typographical quirks, including the page numbers on which they first occur. They should also record all instances of art, ornaments, charts and graphs, excerpts, footnotes, line-for-line text, other difficult formats, chapter starts, part titles, front and back matter, and all the other design components of the book, and should provide page numbers for all occurrences of same.
If the manuscript's page numbers have gotten muddled, they should set things right, renumbering pages if necessary. It's best if they do this before they record the page numbers of design elements, special usage, and proper names.
They should watch out for potential copyright violations (quotations from song lyrics, for example), and flag them for further checking.
If there are problems with logic or consistency -- a character changes their name or eye color, the moon's phases run backward, the tides come in too quickly for the depth of the beach, two rogues act like they know each other when it's clear that this is the first time they've met, someone who's covered with mud is inexplicably clean ten minutes later, the Ringworld rotates in the wrong direction, a horse runs at a full gallop for eleven hours straight, his rider nurses an unsplinted broken femur over the same period, the currency exchange rates of seons, senines, shiblons, and senums don't add up, et cetera and so forth -- the copy editor should query them. A good query identifies the troublesome material, explains the problem, when appropriate suggests possible ways to fix it, and cites the page numbers of other passages that are or will be affected.
If you inadvertently use the same memorable sentence three times in the same half of the book, or if every time a dog gets mentioned it's an akita, or if every time you need a random number it's 56, the copy editor should notice that as well.
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If the guy you've gotten in touch with can't give satisfactory answers, let me know. A lot of good copy editors have had to get used to working from a distance because they can't afford to live in NYC.