All mechanics rack up the price for parts you can get on your own for much less. This is mainly because if the product is defective from the factory it is the mechanics job to deal with the company to get the part or money refunded to him/her to get an undefected part in your car. The increase percentage is for his time to situate the part situation from distributor or factory and the potential loss of money the mechanic will endure to overall replace your part(s). Furthermore, this is also true because a good mechanic will guarantee his work and will fix something for the second time without charge if it needs to be done--its just that the dealer is notorious for jacking up the price on parts ridiculously high.

A perfect example is my door actuator that needs to be replaced-- costs $120+ at the dealer but the same part can be bought online for $60.