2.4ghz does not require you to change frequencies/crystals... you turn it on and your radio automatically finds and open channel and establishes a connection to your receiver. You can run up to 128 (I think) cars within range of each other.

I would look into one of [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXAPPL**&P=0]these[/link]. They're a reproduction of an old Associated model, and have been proven to be pretty durable, especially for the price. Parts availability is pretty good if you order online. If you want something with great local parts availability, maybe look into a Duratrax Evader? You can get the 75mhz brushed version for about $100, they're tough as nails and just about every hobby shop carries the parts.