get the spc 7.4v 5000mah($50) or 8000mah($75) and save some $, unless you plan on racing with these batteries. I have 5 spc lipos, they are great and perform on par with my zippy and flight power lipos. Otherwise, the other suggestions made are great for racing batteries.
HopMeUp is my friend, RcBoyz is the devil.
8ight losi conv MMM 4s Neu 1.5d
8T losi conv MMM 5s Medusa 60-1600-v2
E-revo MMM 4s Feigao 9xl
losi baja lst2 mamba25
xray m18 MM pro combo