Pelican parts lists the radiator for $185. 3 gallons of coolant is $75 if he uses the BMW antifreeze (it's blue), but I suspect he'll use cheaper antifreeze. Probably at least $30. 3 hours of labor seems about right.
Sounds reasonable to me.
Maybe you can talk to one of the locals who posted above and see if they have anything to add. They may have some insights to mechanics in your area.
2001 530i/5 S+P CDV delete/Akebono ceramic pads
M5 SSK/RedLine MTL/M5 rear sway bar/Bilstein HD
BMWCCA Member #337964