You are not allowed any other form of payment for apps in the Play Store. The issue here is that the developer cannot create a Google merchant account from his

You are not allowed any other form of payment for apps in the Play Store. The issue here is that the developer cannot create a Google merchant account from his country, so basically he has to give away stuff for free or leave the Android development. Or start a company in the US. Another issue is that Google has worked out payments worldwide for say AdSense, but for some unknown reason this cannot be applied to Android market.