It depends on what exactly has failed. How many miles on the trans?
If all you have is an input clutch failure (like the OD clutch, the typical weak link), then an input clutch kit (which includes the UD, OD, and Reverse clutch packs) lists for $209 from Mopar. You would also need a new pump cover ($12.50) since the old one is typically damaged when they remove it. You'll probably need maybe 12 quarts of ATF+4®, which runs $5.15 per quart in bulk. At high mileage (on a 2009 or earlier truck) you may want to replace the valve body assy - that would cost $463 list from Mopar. If there are other damaged parts, you'll need to replace them. With a bad OD clutch, you can sometimes need a new pressure plate (usually $26.45) or reaction plate ($14.50). If you're having line pressure issues, you may need a new pump assy, which is $489.
The big kicker, of course, is labor. Pulling the trans, tearing it down, and reinstalling it takes about 7 hours per our warranty labor tables, but they often understate the actual time needed, so I'd figure on 10-12 hours. Might be best to call a few shops for an estimate on the labor.
Do you have any fault codes? Can you explain in more detail exactly what your trans did (or is doing, or ISN'T doing)? That might help me make a better guess at what you might need.