GameMaker Studio 1.4 and many of the plugins for it are currently for sale in the (re)Humble Bundle.  $15 gets it all, if you go for the lowest price point.  After you purchase 1.4 via this method you’re eligible to pick up the 2.0 version at a discounted price ($60 instead of $100 for the primary studio).

A solid tutorial on how to develop your own 2D game art can be found on gamedev.net:  https://www.gamedev.net/articles/visual-arts/the-total-beginner%E2%80%99s-guide-to-better-2d-game-art-r2959/.