It will cost as much as you as you can spend. You could easily spend 50k on you tow rig. Find a jeep you like and see what it cost to build.
I will agree with Imped today. When I first got my jeep I spent allot on it. I bought a new jeep for about 20k and over the next year or so I probably sunk anther 15 to 20k into it.
Know heading out to the park and driving over the biggest obstacle I can and then racing home to see how I can get over a bigger one just does excite me. Now I would rather figure out how to fit fishing gear, my boys, some food and camping gear.
01 TJ, 34 Super Swaper 34x10.5 bias, Winch, locked, belly up, some armor, 4.0, 5spd