How much are you willing to spend? You can get something like an Axial AX10 and just put a Jeep body on it, but it will run you close to $350-$400 for a complete rig.
I'm building this... but it's costing me more than you would think.
Or for about $200, you can get an HPI Wheely King that is ready to run out of the box and a realy blast to jump and crash.... here is mine. The WheelyKing is 1:12 scale, so the HPI Rubicon body won't fit without stretching it's stock wheelbase.
For all kinds of crawling and what not, check out Scale4x4.com or RCCrawler.com