I had my TJ regeared this week at Appalachian Offroad, and couldn't be happier with the service!
Appalachian Off Road -
$750(labor) to regear both axles from stock to 4.10. You can supply your own parts, or buy theirs (Yukon Gear) for the same price. If you get the hardware from them, it includes a 1 Yr warranty.
Contact Mike Bosley. His work is excellent!