It is not difficult and is a fun project. You'll need an AC Commander board and an F3/7 sound & power boards & a pair of electrocouplers. Parts will be about $200. Do it yourself, and the labor is free. You basically strip it down to the motors and go from there.
When it's done you'll feel kind of like DR Frankenstein. You brought an engine to life..
Well, I do anyway.
Go for it. Boxcar Bill can help you out with parts.