I would say, however, that this all comes back around to Yog's Law.
Unless you are self-pubbing, there's no reason why YOU the WRITER should be purchasing large numbers of your own book to get them into stores through consignment. I'm still leery of the idea of renting tables at conventions and selling them there; I've yet to hear a good sales story of that working out.
A legitimate publisher should not count on the author for large-number sales and for them to do the work to get the book into stores. That's the job of a distributor and of a sales/publicity force.
If you self-pub - more power to you. If you're signed with a publisher then you shouldn't be dumping money getting copies of your own books.
With all due respect, there is an enormous amount of "it depends."
Let me give an example.
Although I had never planned on doing so, I ended up publishing an anthology by a group of local writers (you can track it down via my home page easily enough). To my astonishment, right off the bat I had to kick the first printing up to 500 copies because the authors/editors wanted 380 immediately for their own sales to members of the organization, to friends and family, and at events the authors and editors were arranging.
The book is a fund-raiser for the authors' organization, and they do very well on those direct sales.
The authors themselves have arranged signings at several venues, including bookstores. The largest event so far was at a Borders store, which gave me a purchase order for 100 copies that I hand-delivered (billing Borders corporate, which might or might not ever get around to actually paying for the books). Another was at a local independent bookstore that requested and received 15 copies on consignment. Those sold immediately at the event, and fortunately the authors had books themselves to meet the rest of the demand for that day. (Alas, I am still waiting for THAT bookstore to pay me.) For some other events, the authors/editors can do much better for the group by selling directly rather than by my supplying books and taking a cut. BTW, I had to order a second (much smaller) printing because bookstores gobbled up all of remaining copies from the first printing, plus more, and have gone back for another 500-copy printing because the authors are selling the things like hotcakes and want more. (I increased the order so that I'll have enough on hand for bookstore placement where opportunities arise, and for my own direct sales to readers.) What, exactly, is wrong with that?
Another author whose book I have just published wants a supply to take to a conference -- not something to which I could provide books and that could not get them (and definitely not that fast) from Ingram. I'll arrange to get the book into local bookstores myself, though, whether through purchase order or on consignment. But the author will do much better financially on copies he sells directly at his (non-bookstore) appearances.
Another author, two of whose novels I'm publishing (one out already, another coming out in September) wants to make personal appearances. She wants a supply of books for resale (and she is accustomed to that practice with her previous books). For bookstores, I'll place books on consignment or via store purchase order, but for other events, she will do much better reselling herself -- much bigger profit than the percentage of list price royalty I am paying.
But indeed, it is ordinarily going to be a bad practice for authors who are not their own publishers to do consignment sales to bookstores -- the discount will kill them. But
it depends. That is, it depends on who is able to connect with the bookstore owner/manager/buyer, what the dollar figures are (cost of books, royalty, or other revenue split) . . .
Now, what do you mean by "legitimate"? While I have a very small publishing operation (never intended to have one at all, but that is how things worked out -- there are dues to pay for steering people away from exploitive/vanity publishers), I'd like to think it is legitimate. But I am also happy to work with authors who like to personally promote and, yes, even sell their books. Some want to do that. And if so, I can increase my print order to take advantage of reduced cost per copy (and can reduce my financial risk). Win-win.
An author with whom I am well acquainted wrote a book published by a small independent publisher. The author buys case after case of books from the publisher, at the bookstore discount (and gets royalties on those books, too) because every time she speaks anywhere, people want to buy copies -- sometimes several copies each. There is no way for the publisher to deliver books to scattered speaking engagements, but the author is, obviously, already there to speak. What, exactly, is wrong with that? The publication of that book was not predicated on that role for the author, but that is how it has worked out. The publisher still sells books via a wholesaler (which might or might not ever actually pay for them -- that wholesaler has a reputation for screwing small publishers) and via Amazon (which takes an obscene cut off the top, 55%) and directly to buyers, but would be foolish not to enable the author to sell at speaking engagements. (The author usually has sold the books before paying the publisher for them, by the way.)
So, it depends.
Oh . . . distributor? Sales force? Distributors require 65 percent discount (that is typical, I believe), and are picky about what publishers they will represent. (Most will NOT deal with very small publishers with few books.) AND they, too, can and do pay very slowly or not at all. Sales force? Dunno about others, but my sales force is myself, period. Anyway, for books with primarily local or regional appeal, it is not clear that a distributor, taking a huge cut of the action and guaranteeing nothing (not even payment) makes any sense.
One of these days I'll write about my experiences as an accidental publisher. This is an ongoing learning experience. But I am convinced that the platitudes so regularly spouted by those who have not had the experience can be misleading or simply beside the point.
My views, for whatever they are worth.
--Ken