You could run a BL combo form HobbyKing with their Lipos.
Very cheap, comparing with US lipo and brushledd systems prices.
They work very well.
BL combos:
hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10438&Product_Name=Brush less_Car_Power_System_3600kv/35A&aff=143061
hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10330&Product_Name=Brush less_Car_Power_System_5200Kv/100A&aff=143061