You should really think about upgrading to a NV3500 or a NV4500 (hefty), probably cheaper and will bolt right in as well. The 6 speed tranny in the wranglers aren't geared correctly for anything. 1st gear is too tall and 6th isn't short enough.. people are complaining that their vehicles don't feel like earlier jeeps due to this.
As for the NP241 (transfer case) you are looking at 2 grand or so for that if you buy it new, maybe more.. and similiar for a used one.