The wonderous people at YoYoGames have decided that GameMaker: Studio should be half off!
The Pro version is only $37 if you upgrade your 8.1 license!
All of the export modules are half off, excludng the YoYoCompiler, which is still $299.
You can find all the info about the sale at YoYoGames Website.
Or you can simply go to the Store Page Here!