Just talk with your mechhanic! You can use the Estimator feature here to see what the cost should be in your area. Talk to your mechanic and ask him, nicely, to explain why the price is higher. Maybe there is more work that has to be done along with the pump replacement. If you are not satisfied, get another shop to give you a price for the same repair, parts and warranty, keeping in mind the 'quality' of parts used and work performed!