http://www.promatchracing.com/products.php?cat=4
When I was racing promatch battes were some of the best. I got well over 300+ cycles out of them and tons of power
spc also makes great batteries
http://www.spcracing.com/index.php?categoryID=4
Just stay away from the venom and ebay batteries (the e-maxx pull way to much power for them and will cause them to blow up)
The top two links are some of the best and for a good price