"Strike that. You will know that you passed the class when you recoup that investment tenfold. How many other classes you took offer such direct, undisputable grades?"
I doubt you'll make $1k, or even $100, but even if you don't you'll still learn a hell of a lot, so just by doing it you pass the class.
My opinion is that if your app does something slightly useful and basically works, you should be able to make back that $100 easily. Ideally, you'll make more than that especially over the course of a year.
But yeah, $100 is definitely reasonable, and $1k is not out of the question.
Some didn't even changed the images.
And, since the people approving the apps are a completely separated department, they couldn't know and they even featured some of them.
How do you know if you haven't tried? What does it take to make it to $100?
The App Store solves a very nice problem for learning sales: every product is put on an equal footing on the App Store, unlike the wild, wild Internet.
This is not completely true since what Apple decides to promote in the "what's new", "what's hot", "staff favorites" etc spots makes a huge huge difference.