What everyone else said....if you buy a Cobra, it'll probably serve you pretty well. Just understand that four other things will affect how well your CB works:
-What sort of mount you use
-Where on the Jeep you mount it
-What sort of Antenna you use
-What sort of coax you use
You don't need to spend much money on a CB setup....but cheaping out on coax, mount, or antenna will mean that your CB performance will always suck.
Also....you will need to tune your CB. Many members have SWR meters (to tune with), and most will help you out if you happen to ask them while out on a run. Some of us will even be happy to let you stop by our place one evening to help you tune.