No clue how much for the door but i would do the mirror stuff yourself. Just buy the replacement it is an easy fix. My girlfriend's car got her mirror destroyed and i bought the full assembly (with turn signal built in) for $40-60 i don't remember, this was unpainted (you can just give the cap to the body shop to paint as it comes primed). Or maybe they sell it for our cars painted.
GL sorry for the loss!
EDIT:
Found this on GM Parts shop: Little more pricey for us and DOES NOT INCLUDE MIRROR.
https://www.gmpartsstore.com/oem-par...EaAsLZEALw_wcB