This would probably be a better idea:
http://www.horizonhobby.com/cars-and-trucks/battery-chargers-15135--1/2a-nimh-ac-charger-dyn4113
It won't break the bank and will work for NiMH packs like the ones that normally come with you truck. It's a good starting point for now and you can upgrade...
You can also use a 12 VDC regulated power supply that can be found at most radio shops and at Radio Shack.
A good charger is a must and a balance charger is a good investment for the future as it will not only charge the NiMH you currently have, but can charge the newer LiPo and LiFe batteries...