Depends what RC you want:
Electric or Gas
I dont know much about Gas.
For a good electric you can start at 600. I got mine for 900+, and it has all the modifications. All I can get now to make the car faster is a stronger engine. But can can always an RC car starting at 300$ but you will have to modify alot to get to have fast car.
If you want more info just look for me at Lafleurs on Thursdays with my RC Supra or my new RC IS300.
JF