If you have the time, keep your eye on your local Craigslist, Brad....
Roland and Yamaha are the way to go re: electric sets, last time I sat down & A/B'd them the Yamaha had the more realistic hi-hat travel and samples.
You never know what you'll find out there, and it's all dependent on your son's tastes. You could find a '50s Ludwig set for $50, spend $200 getting it in shape, and while it might be the holy grail to everyone else, your son might still think it's a p.o.s...... If you go acoustic, listen to what your son listens to, and approximate what size shells those drummers are using.