Squarehead... I use lipos from a company called Fantom racing here in Michigan. The prices are great and my only complaint is I need to use shorter screws to keep it from getting nicked by those on the top deck. It's a 5400 25C battery that I use in our local 17.5 non boosted touring class. Here's a link and I believe you CAN order directly from them if you find you like them.
http://www.fantomracing.com/products...atteries+Packs
Here's what I use...
http://www.fantomracing.com/proddeta...AN26210&cat=11
Hope that helps.