Are you publishing only your own work through your company?
I set up my own company to test waters with my own work, since going traditional wasn't such a picnic for me. If I'm going to end up doing all the work anyway, I might just as well do all the work and get all the money, however much that might be. I haven't made a lot, but--I have made more than I did with a traditionally pubbed book.
I bought a block of 10 numbers which costs, last I knew, $280. It's not really enough for all I wanted to do because I have more than one book to put out, but, it's the cheapest way to go. Next is 100 numbers for $800. I'd like to shoot for that at some point. But until then, I'll just keep getting blocks of 10.
If you live in the US, as far as I'm aware, then you have to get your numbers from RR Bowker, USA. I'm pretty sure you have to follow procedure for your respective country.
But, maybe, someone with more knowledge will hop in and set the facts straight for us.
I have heard of people publishing without them, but they are not selling their books in bookstores or any other retail place. They sell primarily out of the trunks of their cars, conferences and workshops, other places where they are appearing publically and can do back of the room sales, and off their websites and blogs. You can sell eBooks without ISBNs as well if you're not looking to get online retail stores to carry them. They don't need them if you're giving the books or eBooks away for free.
You need a number for each format you publish in, so they advise. But a lot of us are using one number for all eBook formats. With five books out, my numbers will be gone soon's I am able to do print runs for them. Or maybe, I should just not save any numbers until I am ready to print, and then go get new numbers for that!
Decisions decisions, decisions . . .!
Then, there are copyrights to consider, book covers, promo, marketing, etc.
But it is possible to get the word out in low cost and no cost ways. I need to try some of those . . .
Anyway, hope this helps in some small way!
Anita