This may sound funny, but one of the best cheap planes you can buy is the AirHogs Aero Ace Biplane, which you can get at Toys R Us for about $25. They are indestructible, and can be flown in your backyard or a gym. They aren't like flying a 'real' r/c plane, but once you get the hang of them, they can be a lot of fun.

http://www.toysrus.com/product/index...ductId=2402681

They can also be found at Target and Walmart