I lived in that area for most of my life. There a bunch of custom builders, but the only BD Dealer I see in up in Santa Rosa, north of San Fransisco. A good friend of mine is in Santa Cruz which would be a fun side trip. Scott Long... check him out at :: Central Coast Cycles ::
It's about 20 miles from Fremont to Arlen Ness located in Dublin. They've got a "museum" upstairs in their Dublin dealership that is pretty interesting. Check out their web site for more info at: Arlen Ness