Here's my cunning plan.
How about an app that lets you rent other apps?
I know it sounds crazy but just hear me out.
You want an app that lets you work with various documents whether they be text, spreadsheets, presentations etc. or maybe you want an app that will let you use your imagination to paint a picture. In fact, anything where there are lots of apps that might fit the bill but you don't know which one to get.
Download this one App and tell it what kind of app you are looking for. It scuttles off to search the App store and comes back with 10 apps. Then you use the "Collector" app to pay a rental fee of say £5 to use the apps for a month while you decide which is the best one to actually buy.
Is there a downside to that idea that anyone can see?
Get to it all you keyboard wizards. :D