I recently ordered a GM 3-bar MAP sensor and harness through gmpartsdirect.com and discovered after I had placed the order that I was charged for shipping/handling on EACH item. The price of S&H varied according to item cost, in other words, the more expensive the item, the more expensive S&H is. Strangely, the harness for the MAP sensor is larger than the sensor itself. Neither is larger than a pack of cigarettes. In their defense, they commented that they sell at 20% above advertised dealer cost and the S&H went to cover other business expenses such as the web or phone services. Isn't that what your 20% markup is for? To me, it's a simple bait and switch tactic. Advertise a low price and then "surcharge" the customer at the tail end to make up the cost (and hope the customer didn't notice). To top it all off, I checked with the local performance shop and their prices were lower. Buyer beware.
Michel