I've seen these range from 600-1000+, but then again, most of us know that dealerships do tend to overcharge. Even if we can justify their high labor rates, I'd bet you can find parts *much* cheaper than what they sell them for. So, even if you are not mechanically inclined and/or don't have the tools/time etc., you could save some $ by getting the parts from a place other than the local dealership counter.
However, if you do that they may not be inclined to "throw in" extras
To your point about reselling the car, others may disagree, but I strongly believe that a potential buyer would prefer a dealership serviced car, and even more so if the buyer is a p-car novice. The only exception would be if the shop that did the service on your car is very well regarded (and the buyer knows of them).