I know that android is easier, while iOS is very difficult for indie devs. For a Google developer account, it's 25 USD and it's permanent, but iOS normally requires a Mac to compile and costs 99 USD a year to keep apps available, and unlike android where you can install APK files from unknown sources, to install IPA files on iOS you need to jailbreak the system. Don't worry as only 1 fourth of the mobile community uses iOS devices, and if they have the money for one, they can probably get an Android too.