Sorry about going on about the publishing details, but after 20-some years of writing and arting, I'm putting in a couple years on marketing and publishing. About now I'm the go-to girl on all levels of publishing, self, print-on-demand and Naked Peacock.
Naked Peacock: a site that is very simple and basic, like a plucked chicken, that automatically pays authors for their books, the webgang a fee, and tracks everything through a simple site like CCNOW (credit cards and Paypal, both). Even pay back customers who help promote the site (why not?P). The users stick all the pretty feathers on the site to make a peacock, but the chicken stays simple.
The entropy can only happen to the feathers, and only if they're not properly groomed by individual users. The chicken stays fresh. CCNow has stayed sleek and useable because they don't care how any of us build our carts, as long as they're legal.
Amazon is an example of confusing the chicken with the feathers; at this point they're reverse-engineering to a dinosaur.
I don't even know if CCNow even has this capability to feed fees into the correct lines, but because they're a Naked Peacock themselves, I will bet they can tweak it to work for a book industry site.
(Another nice NP is ProjectWonderful)