To save some money on paint if you're not in a hurry...When you go to the auto body shop, you can ask the guy if you can leave the fender at his place and ask him to wait until he is priming and painting a car with a similar paint color and to spray it with his leftover paint. To match the color he may just have to adjust a little what he has left over. I'm sure the primer doesn't matter much.
My brother did this at a local shop. He sanded and primed the fender himself then left the fender at the shop. When the guy finally painted a black car he painted and clear coated the fender for something like 30 bucks. It took a few weeks though and he knew the guy, and black was easy.
You'll pay a lot more of the guy takes it on as a stand alone job and has to prepare, prime and paint the whole thing.