I just bought the Pro-Match 2s 5000mah 45C lipos w/ hard case. I paid
$75 ea for them. They are awesome. The Slash 4x4 will take a 3s but I think that is way to much power for indoor. Stick with the 2S. I p
I have read up on the one's at Hobbypartz. They seem to be good also. Haven't tried them though. The only brand of Lipo I would absolutely stay away from is Venom. Hope this helps .