It's much more app-specific than the market for novel-length fiction. Think about the differences between a fart app, a simple game like Angry Birds, a more complex game like a FPS, a simple utility, and full-featured productivity app like Omnifocus. There's no single ideal price point that covers all apps.
I can pretty much guarantee that every developer has done some A/B testing on price points for their various apps. I make Facebook game utilities. I've found the ideal price for those kinds of apps are $1.99. At $0.99, I don't get significantly more sales than at $1.99, but I get a hell of a lot more negative reviews. For what's essentially a Farmville Reference, at $0.99 I get people complaining that the app doesn't let them play the game or integrate with their farm at all. At $2.99, I still sell well, but earn less money than at $1.99.