I Still think it's white silicone. Which is similar to the body shop's gasket maker guess. I've removed silicone from paint with a plastic putty knife, some heat, and a lot of rubbing/elbow grease.
I agree with IND, that's too expensive, you should get another estimate.
2008 IB E92 M3| BBS | KW | Arkym | Platte Forme A.G. | Active Autowerke | K&N | Fabspeed | Dinan | Evolve-R