In the Amazon business model, there's no advance, and often no agent, although some agents are beginning to participate as publishers. I have to say that my sympathy for the big commercial publishers (not that Amazon isn't or won't be one soon) is very limited. They dropped me unceremoniously 25 years ago-- well, not entirely true, that was Scribner's. My last big publisher was HarperCollins for the Marco kid books, and that was only fifteen years ago-- anyhow, the bottom line is, Conventional publishers dropped me and a lot of my friends-- mid-list and literary writers of high repute and great accomplishment-- and we've been scrambling ever since. I've used small presses, nonprofit presses, university presses, cooperative presses: I've published with all of these, as well as with Scribner's and HarperCollins, and had Sc & HC been more nurturing of me when I was not a best seller for them, I might be less ready to embrace the Great Change going on now with ebooks and self publishing. There are myriad problems including, at the very least, who are the gatekeepers, but also vast opportunities. And for me, a lot of fun too. The opportunities include simply being able to make books available to people who who might want to read them-- miniscule numbers beside what bestseller oriented publishers except, but human beings, readers, communication. I have been having a great time with my various ventures.