I normally stay away from pricing questions...but yours really got my attention when I read it. The simple anwser is yes it does sound excessive. At 30K normal service Buick calls for a few inpections, oil, and oil filter change,doors lubricated and a wheel rotation. $150.00 max. Is there more to this than other than 30k maintenance service? Did you need a new set of tires or did they sell you every upsell item in the book?
They charged $633 for labor and the balance for parts, coolant, oil, filters, wiper blades, fuel injectors, decarb kit, and other abbreviated items that I cannot decipher. They claimed this is the standard amount for the 30,000 mile service.