DH has self-published a book. A little part of me feels sad he didn't get the recognition he would have gotten with a 'real' publisher, but DH has very strong views on intellectual property laws etc, and wanted to make sure his book would remain copylefted and able to be accessed for free online. AFAIK that's virtually impossible to achieve with a 'normal' publisher.
The service he used was called 'Lulu'--US-based, I think. There's no upfront cost, you just send them the PDF or whatever, which is *exactly* how it'll end up looking (your margins, your typos--they don't edit it at all). They say 'Okay, it'll cost us $12 per copy to print it' and you add your 'royalties' on top of that. So if you sold the book for $20, they'd send you a cheque for $8. Make sense? DH has gotten his first quarterly payment, which was very exciting--he's only sold about seven copies, but given the subject matter (presuppositional theology), that isn't too surprising.
I really don't know how self-publishing works with illustrated books though. You could check out the Lulu site and see if they had any info on that. Good luck!