Buying an ISBN?

Unfortunately, if you're a US resident, there's only one way to buy an ISBN that would have your name attached as publisher of record--direct from Bowker. They're pricey, but they often have sales on buying 10 or more.

When I bought mine back in 2009 through Bowker, a batch of 10 sold for $275. With your ISBN prefix application, you also got a link that would generate the bar code that went with it.

In 2019, one ISBN goes for $125. 10 ISBNs go for $295. So if you're planning on doing multiple formats (each format needs its own ISBN) or multiple projects, the 10 ISBNs would make sense by your third item.

100 ISBN's go for $575, if you're planning on doing more than 10 things.

I'm curious why you want one. Unless you're making a run on the USA Today best seller list (and being exclusive to Amazon, you can't do that), it's an expense you can avoid.

another possibility is to go in with a friend on a set of 100.

I've gone back and forth on the ISBN thing. I'd like them because I want to publish hardbacks through Ingram, but it's hard to justify almost six hundred bucks at my level of sales. But Laer has been doing this longer, and she's seeing some more success than me. Investing a chunk like that might make sense for her.

Sorry, I'm late to this and very new to the self publishing game. The free ISBN from Amazon won't work?

The Amazon number (offered for free) is only applicable to the Amazon market; it can't be used anywhere else.

In all other markets, you'll need a separate ISBN for each format (hardback, paperback, and each ebook format - epub, etc.).

https://www.isbn-international.org/content/guidelines-assignment-e-books