can not help with the dealer costs. I would have the brakes done by a shop that specializes in brakes. The sound is not good, indicates that the brake shoe/pad material is gone and your making metal to metal contact. The repair cost just keeps going up as you continue to drive.
The rotors and or drum must be smooth and have a minimum legal thickness AFTER they are machined smooth.
The cost will vary with machining costs and/or whether parts must be replaced.
I have found many dealership do not have the equipment in shop for the repair and they the parts out for machining to another shop.