I think "affiliates" may have a bad vibe, but you could message it in a way that wouldn't. I know Gumroad is coming out with some functionality along those lines and they call it "tastemakers" or something similar.

I bet you could significantly increase your revenue by working directly with authors—though if you try to republish their books it would be more work for them.

Just work with one author a month, whose book you have carefully vetted, and promote it to your lists for a commission.