A decent pro level RC starts out around $300 for the kit, motor, controler, etc. Most hoby shops will build them for you, but that is half of the fun. The cool part is that you can select everything you want for the use that you intend for the RC. When I purchased mine, I was looking for speed and good handleing. I went with an HPI RS4 MT, 4x4. It works realy good on dirt tracks but is geared to high for rock crawling. You can also change stuff as your needs change (motors, gears, locked diffs, diff gears, transmissions, etc...
Later,
Zig