I own a repair shop and yes we do mark them up, most shops are around double what they pay for them at the parts store (mine is not that much), if you do a large volume like I do you get a significant discount over a walk in customer. Reason is when parts are wrong or go bad in the warranty period we often times have to eat the labor not to mention the hastle of getting the parts store to give you new parts and asociated parts. If you bring your own parts to me I am happy to do the work for you but I am not doing them free when your e-bay remans go bad or don't fit or... If I supply parts there is at least a 12 month 12,000 warranty where you bring it back and don't worry about it when they go bad I just fix it.

The labor time on there is only 3.6 hours, that is about right on in my expience.

All this shows why I don't drive a diesel, I can replace my whole truck for little more than the price of injectors on yours. I just replaced a complete V10 engine in a customers truck $1400 out the door.