another good tip is to find dealers that are aware of enthusiasts for a particular model and stock parts / charge prices that are designed to attract them.
when i owned my lincoln mark viii, there was a dealer in arizona that could beat Ford list by 60-70 percent.
now that i have my cadillac cts-v, i only buy parts from Lindsay Cadillac in Virgina, as their parts manager, Luke, beats GM list by a huge amount and almost always has what i want in stock - which is important when ordering for such a rare car.