ISBN 1-88446-00-X
Nearly all smaller publishers use Lightning Source as their printer, distributor, and marketer. Some of Lightning's stuff is kind of hard to find on their website -- like their File Creation Guide and their Publisher Operating Manual (includes current prices pp.8ff,20ff). Here is a book about using Lightning.
Last time I checked, Lightning charged a setup fee of $75 for receiving and checking your digital files for cover and text ($37.50 each). They also charged $12/year/title to keep books on file in their system; they just store the computer files; then they manufacture each book as soon as it is ordered. At last check, they charged $.90/book + $.013/page for each order, for a "small" (5"x8" to 7.5"x9.25", 108pp to 1200pp), black-and-white, color-cover paperback (print-on-demand so that's both the quantity-1 price and the pallet price). Amazon appears to be happy keeping only 20% of the list price; and all shipping costs come out of either Lightning's or Amazon's shares.
You do everything required to get your book turned into an error free .pdf file, then Lightning handles all of the printing, shipping, setup with Amazon.com, marketing, and billing, and pretty much everything else. They send you the "gross profits" (sale price minus Amazon's 20% cut and Lightening's printing and maintenance charges).
The downside is that Lightening only deals with "publishers." However, this isn't really as difficult a problem as it sounds. This book here and the other book linked above (and below -- same author) explain all of the hoops you have to jump through to become a "publisher," like getting ISBNs, (which you get here) etc. ISBN numbers can be a little bit pricey in small quantities; most publishing houses buy them in large enough quantities that they don't cost them much.
Of course any of the rules can change at any time. The author of the two books (linked above, and the first four linked below) maintains a webpage, here with information to keep his customers posted on the changes. It's also a sales tool, so he probably won't object if others use it too.