Our App is an educational game, Steve Storm and the Tables of Doom, it is a $1.99 app with no in game purchases. It has no been out 2 months and we have sold around 600 a month. Sales have now slowed down to about 10 a day. This was a relatively expensive project and we will in no way directly recoop costs. In our situation the app was also a branding exercise and we can hopefully gain indirect customers.
I would not spend such a large amount of money again. In my opinion app sales and the inability for non-free apps to earn back costs is a major problem. If we make another app it would have be significantly cheaper to make and much more thought needs to go in to monetizing within the app. I have some clear ideas about what I would like to do in that regard. Even a cheap to produce application is expensive if you create it in a business environment, I am not talking about hobby developers. If you cost the time and effort a simple app quickly costs many thousands of dollars. You need to sell a lot at $0.99 to earn that back.
Because of the significant development costs and the extremely low return developers are not likely to create the kind of apps I would like to see.