You could try Weissach, at
http://www.weissach.com ... they're about 5 minutes away. They do all my wrenching for me, and go out of their way to help people. They've also done some incredible work on a 350SL, etc.
There's also a Mercedes dealership a little closer, at basically the 1300 block on 9th (Broadway).
http://www.mbvancouver.com/index.cfm?id=3314
Don't know any others.