1. Best case scenario would be the o-rings on the barrel are cut or deteriorated and we can swap them out in about a half hour. You'd have roughly $75 for parts and labor on the barrel o-rings, $250 to max and balance the pump, and $75 if you want the lock-timing location changed.
2. Worst case scenario would be you have a barrel cracked and the whole pump would need to be completely overhauled. If this is the case you'd be looking at $800 for the labor, gaskets, seals, and calibration of the pump (total teardown and cleaning). The cost of parts would be additional, but if it is a b&p issue we have a stockpile of like-new used b&p's we could install and save you money.
You're best bet is to call the shop and talk to myself or Rodney 877-367-3835 and we can get more info and possibly get you scheduled if need be.
-Seth