A $0.99 price point only makes financial sense to a developer if the potential market is rather large, which is just isn't for a Solo specific app. How many sales do you think he's going to make, a few hundred, maybe a thousand or two? Developing something like this for two grand, of which Google will take a third, just isnt worth the time.
You have to look at it based on what it does, not on what other useless apps are selling for. This makes a $1000 tool more useful, and as such, $30 isn't asking too much.
A set of props will set you back about the same as this app, and with 3DR effectively done adding features to the Solo, this app is the only hope for anything new.
I have no problem spending $30 on this, even if only to support a developer who took on such a task. This is not like banging out the umpteenth clone of some game using the same game engine everyone before used.