I had an ignition cylinder keyed to match my doors, had keys cut from the cylinder and I think it was around $30. Are you talking about having the lock rekeyed to match the rest of the locks in your truck or the actual install?
i'm not sure exactly how it's broken, but when i found that my tailgate lock was just frozen due to sitting/non use and needed a good shot of WD40 and all was good again. my truck seemed to have gatherd more than it's share of dust and grime in every possible nook and crany possible.
just in case, could save you some $$$.
of course if it's really jacked, then this info is completely useless.