I've used CreateSpace to sell and order copies of one of my comics! I think it's very fair, I sell the 127 paged books for $15 and can order copies for myself at a little less than $3 each (last time I ordered them) to sell at cons and such. The only fees are really just processing ones when you do make a sale as with any site where you can sell your own work, I can't recall the exact percentage, but it's not enough that I feel gouged. So I can't imagine it's much different for strictly e-publishing.
I really like it because you can order so many proof copies and edit your document an unlimited amount of times, you just have to pay for the proof copies and their shipping, which again run for fairly little.
Haven't had experience with epub yet, but I might look into it when my novel's done.