Map Right Command Key to Escape? Quite simply, I'd just like to modify the right command key to escape and that's it. Keep the left command key as is.

The only tool I've been able to find for this is ControllerMate but I'd rather not pay $14 to map one key.

Can anyone suggest a free alternative?
You can download Ukelele. It is an free keyboard layout editor, and you can make a new layout for your keyboard where simple redefine the keys. In the package are sample keyboards and a manual/tutorial too.