You can get cheap batteries from
[url=http://www.hobbypartz.com/]Shop for RC Hobby Parts and Upgrades - Digital Servos, Brushless Motors, ESC, LiPo Batteries/Chargers for RC Helicopters, RC Planes, RC Cars, Robots[/url]
[url=http://www.hobbyking.com/hobbyking/store/index.rc]HobbyKing Online R/C Hobby Store :[/url]
I have the new hobbyking 100c batteries and I am current testing them for a review that I will post on the forum. For a 2S it only costs $30.