I'm sure the same would go for them as well. I've heard that self-published books usually top out at around $500 in sales on Amazon for decent books. At the avarage price of $9.99 that's just over 50 books. Self-published books for the Kindle would probably do a little better, especially is the price & the content is right. And putting books in the iBookstore for the iPad, iPhone, and iPod touch is free :o