If you want to spend all $500 get the Team Kit, an engine, a radio, a fuel filter, good air filter. That'll put you right around $500, maybe a few bucks more.
I'd stick with the origonal idea of the RC10GT, but I'd get the RC10GT Plus, only thing left to buy is fuel and batteries, and whatever hop up's you want, like aluminum arms, turnbukles........
I am RC10 GT is a good choice. I do want a true stadium truck and am thinking of the XXXNT Drake edition. It looks mighty nice. Anyways I am sure whatever you pick you will be happy. You may want to stay from Duratrax though. Also another thought check out what parts your Local Hobby shop stocks cuz I know I totally hate it when my hobbytown has nothing I can use. Late