Pardon me while I think

I am working on another ebook.  Yes, despite the fact that my last effort earned me about $0.05 per hour, I haven’t lost the yen to publish.  This time around, I think I’ve got a better idea for a book that will actually see me making a more reasonable return on effort.  The book is more focused, has a broader potential market, and is shorter.  I’m not going to ill-wish myself by telling you about the book yet (I’m still blocking it out and am riding a lovely wave of ideas), but I’d like your input about one thing: When you’re buying a self-published ebook, what’s your preferred purchase price?

My sense is that, if I price too low, I make it look as if my book is valueless.  However, I learned the hard way with the last effort that, if I price it to high, too few people are going to buy a book from a self-published author.  I would very much appreciate your opinions on this.