Are you in Oregon by chance? if you're anywhere near Portland, there is a super cool place called 'surplus electronics' out in Beaverton/Hillsboro. I'm pretty sure they had those around, for quite cheap.
Pro-tips for noobs: Avoid BMS Battery like the plague | Charge RC Lipos to 4.15v, stop discharging at 3.5-3.6v | Use torque plates/arms! | Rear mounted hubs are always best