$3,000 for a head gasket replacement on an M103 is outrageous.
The M103's are notorious for valve guide wear, so I don't know a mechanic that would just do a head gasket.
A head gasket with a valve job, new guides and seals, should cost around $1,200.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".