Ouch. That's outrageous. Is it $620 for just the parts, or is that installed? Mirrors aren't too complicated to remove and replace, the only thing is they generally don't come pre-painted, so you would still have to have a shop paint it unless you want your car looking weird.
For what it's worth, here's my story:
Everything went fine until I reached the end of the car wash, at which point one of the air ducts came loose as the dryer turned on, and the metal-reinforced ducting fell down on the car I had bought just a week prior, leaving a trail of scuffs and scratches behind as it dragged along the paint. Believe it or not, I wasn't even that mad about it until I showed it to the manager. To say that he didn't care was an understatement, I mean he didn't even try to fake being concerned, it was more of an "okay whatever, now leave me alone" type of conversation.
The dealership I had bought from was located across the street, so I drove over there and had their body guys take a look at it. The scratches weren't too deep thankfully, and they were able to buff it back to a mirror shine. No charge, and they even gave me a cold beverage to enjoy while I waited. Nice guys, and they got a lot of repeat business from me. The car wash, not so much.
Anyway, for the past 20 years now I have only hand washed my cars and used the touch-free type in the winter.