I think this is the wrong question. I think the right question is "Is this repair shop honest?" If the answer is "yes" then the price is reasonable; if the answer is "no" then the price is not reasonable. The brake job analogy is imperfect, because there is a "book" that tells all shops how many hours of labor are involved.
Did the repair shop break down the cost in terms of cost of each cap, cost of various parts of the labor (remove old caps, replace with new caps, test, etc.)? That should give you some idea. If they did not you might want to ask them to do so. You don't know how much labor is involved but you can find out what the caps would cost.
Did the repair shop break down the cost in terms of cost of each cap, cost of various parts of the labor (remove old caps, replace with new caps, test, etc.)? That should give you some idea. If they did not you might want to ask them to do so. You don't know how much labor is involved but you can find out what the caps would cost.