Your time is of course the major expense involved in supporting a new platform. That is especially true of supporting Android, because Android development is f

Your time is of course the major expense involved in supporting a new platform. That is especially true of supporting Android, because Android development is free, and you don't need to buy any hardware to test your application. For simple apps like yours the Android SDK's emulator is very accurate and runs on Windows/Mac/Linux. (See http://developer.android.com/sdk/ http://developer.android.com/sdk/ ) The only money you would need to pay is when you want to publish your application on the Android market. It costs around US $25 to become a registered developer. For other people considering cross-platform mobile development, for simple apps, one way to keep costs down is to use one of the approved-by-Apple cross-platform development environments. The one I've used is called PhoneGap, but I think there are others. You write your program in JavaScript/HTML5, and it is run in WebKit on all mobile OS's that support WebKit. (Android, BlackBerry, iOS, WebOS). PhoneGap isn't exactly polished, and it's not quite write-once run-anywhere, but it is still probably the fastest route to getting a simple app up on multiple mobile platforms.