I've made a few bucks on Risen, enough to make it worthwhile to post and sell at $2.99. I give away the short stories that tie in with the novel.
This was a previously-published book, however, which lowers the bar.
I'm working on a second novel but I don't have any interest in publishing as I did with Risen, where it takes years to get a six-month spot on the shelves and then the book is dead for another seven years. I'll go straight to ebook, but I might want to find a small publisher for credibility, even if it means making less per book. I haven't decided yet.