If most of the local guys are running TC3s and TC4s then that would be the best to start with. If you need set up help, it's there. If you break something, chances are you will find it at the track if there is not a shop on site.
Chech out ebay or the "For Sale" thread here to find a good deal on a decent used one. Try to find one with extras like tires/wheels, body and spares included. It's cheaper to get a used car with parts then to have to buy them new from the hobby shop. That way you don't have tons of money invested if you change your mind.