Well, I went ahead and invested in a block of ISBNs for the Arachis Press. That was the last thing I needed to decide on before finishing the new book.
I went for 100 numbers. That should last the rest of my life. Ten almost certainly wouldn't have and each number would have cost almost five times as much. I can live with this modest investment, even if they prove to be of absolutely no use!
I just might apply a couple to the books I already have in print, on new editions, but there is no hurry on that. Not sure it makes any sense to use one for these small books, anyway.
I also suspect that the whole system of ISBNs and UPCs and barcodes may become obsolete. As computers continue to grow 'smarter' and more powerful, numbers and barcodes will become less and less relevant. They'll be able to find stuff by name, read the text from covers, etc.
For that matter, just look at the file systems on these machines we're using now. We can find pretty much anything with a word search, no matter where we 'mislaid' it. As we can on a larger scale with search engines and the entire internet.
Soon we'll be able to do the same in our warehouses or stores. The whole barcode concept was really developed before the modern computerized age.
Would one look for an ISBN on Google? Well, maybe in a few rare instances, but in general it would be title or author or publisher or even subject.
This also means that the big stores, the Amazons, the CD Babys, are becoming less relevant. We can all sell direct these days (if we wish) and search engines will bring the world to our virtual doors. The goal will be to be discovered -- once that's done, the selling part is simple.
So social networking is the place to put ones efforts. Make people aware that you're out there and have something they want. Get your music where people can discover it. Give it away if need be. Have your book cover and blurbs plastered anywhere you can. Get reviewed!!