This is a great idea, exactly what I was trying to get at in my comment elsewhere: https://news.ycombinator.com/item?id=17821945

This seems like a pretty good idea. I'd be curious to see how many apps are sold for prices over $20 USD, as my impression was that the vast majority of paid apps were competing at lower price points.

That's an interesting idea. It might even encourage developers to work on higher quality apps, or to not devalue their own software.