What? 50 dollars per book? And 5 % of sales? I upload myself to all three (Kindle, Nook, and Smashwords) and get 70 % (if the price is at least 2.99). And I set the price of the book. Why negotiate? Amazon offers the same deal to everyone.
My expense is for formatting alone (because I don't want to be bothered with it) and there is a surcharge for Smashwords, which suggests that it has special problems.