Whether you're preparing to publish for the first time or are an old hand at it, your work is going to need an ISBN. The International Standard Book Number is the identifier (i.e. fingerprint) for your written work once published and made available for sale. If you only plan on making a single version of your book, magazine, comic etc. you'll need one ISBN to identify that work.

Keep in mind that having an ISBN on your work does not mean Copyright or ownership by any standard. Unfortunately, if you plan on distributing your book in multiple formats (i.e. Print, e-Book, Audio Book) you will be required to have different ISBN's for each version.

The really bad news is; ISBN's are expensive. There's only one official seller of ISBN's in the US (Bowker) and let's face it, they are in business to make money. One ISBN costs $125 and that's basically to discourage (for lack of a better descriptor) 'Broke Hobbyists'. ISBN's do get cheaper the more you buy down to $1 a pop (but you have to buy 1000 of them to reach that price!)

The better option most will run with is purchasing a block of 10 for $250. That breaks down to $25 a whack. Why do they cost so %$^#@in' much you ask? Because. That's why. Move along, nothing to see here. The block of 10 works out particularly since you'll need 3 versions anyway (1-Print, 1-Kindle/Nook, 1-Apple Store/PDF.) Good news is; if you have three more books planned, you will already have the ISBN's and won't have to buy them. Of course, you'll have one left over so save that for something you only plan on putting out to electronic publishing.

Now the part where all this gets into some seriously 'Gray Area' is when you publish with Amazon or similar distribution outlets. Amazon's Createspace has a great setup for both pros and amateurs to get their books setup and published. If you're a pro or have access to one I strongly recommend using their 'Do it yourself' options. I've published two books with their old version 'Booksurge' and used that option each time and saved some money. Now, those options are free (but you'll have to seriously dig for them in their website to find them.) If you don't have the skill and knowledge or access to someone who knows how to put a book together for publishing, then certainly use their professional services to get your book done. Just be prepared to fork over some serious cash!

That 'Gray Area' I mentioned comes when it's time to get your ISBN with Createspace. Yeah, they'll give you a 'free ISBN', but keep in mind it's theirs not yours. Because it's their ISBN you can only use it within their distribution network. Now that's not necessarily a bad thing as Amazon has a massive distribution setup. The 'Grayness' comes in that Amazon has it's own identification system so if you get with them your book doesn't really need an ISBN anyway! So those offers of pricing for ISBN's for independent publishers Createspace has are a ripoff. If you want to own your ISBN's, you're better off forking over the $250 and getting them from Bowker.

For all you first-timers, pay attention. The goal of the novelist is threefold; first write the damn book, second is to get it published and third is to sell it. The most important aspect of all is all creativity aside, you're in this for the money! A manuscript is just a big block of words until it becomes a book. A book is just a bragging point until you can sell it. Unless you plan on giving your hard work away for free, this is business.

So the goal is to create the work, prepare it for publishing and distribution for the LEAST AMOUNT possible! If you're going into debt trying to get your book published, you're spending too much money! Remember, sales of your book need to first recoup your expenditures for getting the book made (cost of artwork, editing, publishing and printing/shipping fees.) Once those expenses are recouped, then all sales after that will be profit. The more you spend up front, the least likely you will be able to make a profit.

Now, I haven't published with Barnes & Noble or other outfits, but you'll need ISBN's with them as well. You'll no doubt run into similar issues with any outfit you self-publish with. So to give you more info on what and why you'll need your ISBN's for, here are some good articles breaking it down. Some of it's pretty basic and you pro's may wrinkle your noses a bit. However, it's all solid info and there may be stuff you might have missed.

http://bookcoaching.com/wp/do-i-really-need-a-separate-isbn-for-my-ebook/

http://www.thepassivevoice.com/03/2012/isbn-for-self-publishers-answers-to-20-of-your-questions/
http://www.thebookdesigner.com/2010/03/isbn-for-self-publishers-answers-to-20-of-your-questions/