I know this is exactly NOT what you asked for, but I have to throw this in. I called the dealership where I bought my car the other day and asked to speak with the parts manager (Robert @ Holman Honda in S. Florida). I respectfully let him know that I, as a weekend wrench, had numerous online resources where I can buy OEM parts AND accessories. I asked if he would consider matching the prices I was finding online; even at those prices they are making a profit. To my immense surprise, he acknowledged the necessity for a realistic approach on a case by case basis for customers like me in the age of the internet. Give your local parts people a shot and see what they say.
Shipping costs, availability and part size also play a major role depending on where you are and what you are ordering. An expensive, albeit small, electrical part may be worth a little haggling. There are some places that just drop-ship through warehouses. If you find a shop that charges a tad bit less for shipping and you plan on ordering a bunch of stuff, but they are a tad bit more expensive, then it may be worth calling the cheaper shipper and asking them to match a competitor's price. They can play with their costs all day long; however, their shipping rates are usually set. Again... Usually.
If dealership distance is an issue and it's more convenient for you to have them to ship to you, then: Majestic, Handa and Bernardi come to mind as being great suppliers. I have personal purchasing experience with them and had no problems.