For the $$$, it's hard to beat the Uniden Pro520XL, it can usually be found for $50 or under by using shopping sites like Google's www.froogle.com
. The Pro510L is similar but less $$$ because it doesn't include a PA function. If you don't need/want a PA, the Pro510XL will work well. I'm no longer a fan of Cobra brand CBs, I don't believe their current quality is anywhere near what it used to be when it had a solid reputation. Midland is another good brand whose quality is similar to Uniden's.
You'll need a antenna like a Firestick FS-2, FS-3, or FS-4 with the number being its height in feet, an antenna mount to hold the antenna itself, and a bracket to hold the antenna mount to the Jeep.
This bracket is not the one I recommend but it shows how the antenna mount is positioned on whatever mounting bracket you choose. I recommend the mount from Teraflex with a link to it below.
You'll need the right kind of coaxial cable which is RG-58, not RG-59 which looks the same. No specific length of cable is needed, some will claim you need precisely 18' but that is just an old wive's tale.
Sites that sell CB radios like the one I recommended above (and have used in both of my TJs) normally have the antenna mount & cable.
A good source of a mounting bracket would be Teraflex, you can see what they offer at Search | TeraFlex Suspensions
The best all-around type of antenna mount is like this one...
That mount must be assembled exactly as the instructions say, otherwise the antenna won't work... don't fail to position its insulating shoulder washer exactly as instructed.