How much for a buff and paint on a Prius bumper?

I was in the drivethrough line at mcdonalds today and i rolled into the back of the prius in front of me. the damage was two scratches about 3 inches long on the bumper with loss of paint but no structural damage to the bumper. how much would it cost to buff and paint the bumper? i want to avoid the insurance co. on this one but if it does get claimed do they distinguish between such minimal damage (this could have happened parallel parking, for example) and a bona fide collision?