GameSalad is the world's most advanced game development tool for non-programmers. From an easy to use logic and physics system, to a visual based interface, and even the means to share your games to the iPhone, iPad, Desktop, and Web - GameSalad provides everything you need to get your game from concept to execution. Simply download the tool to a your Mac, install, and start making games!
The quoted price is for the Basic subscription, per month, paid annually. Pricing info can be found here.