I'm making basically a radio controlled 4 wheel drive "mule" to haul stuff around. Needs to go 5MPH and will weigh about 200lbs and carry another 200lb in payload. Here is what I found already, please comment if you have a different opinion!
Motors - A 24V electric wheelchair motor for each of the 4 wheels (will steer like a tank)
Controller - Vantec or other controller that can do about 60A continuous total
Radio - 3 channel PCM 2.4GHZ