Youtube video of some Traxis E Maxx trucks going through what looks like a small obstacle course. Looks pretty nimble to me but these are not stock RC cars.
I saw the E Maxx for about $300 RTR or Ready To Run.
$80 for larger tires pre-mounted,
$35 for pan/tilt with servos from lynxmotion
$150 for 5.8ghz video transmit/ recieve system from Radio Shack, but only good for 300ft.
$300 for complete system from www.rctoys.com
that transmits up to 1000ft.
$50 for Misc stuff.
$650-$800 for off the shelf parts.
This of course is not including the paintball marker setup and a better radio system to include control of the paintball marker setup.