Ever since the introduction of app stores there has been a whole new industry built around apps. Apps are big money even though the average price of an iPhone app is $0.19, most of the developers who make the most popular apps are millionaires.
But obviously as with any market like the App Store there are always some people who like to have some fun. Some apps go for a crazy $999.99, which is the max price you can set for an app. Here is a great infographic by TopApps showing 16 of the most expensive iPhone apps.