Steve, I guess the point is to know one's limits. I doublecheck information I get online with my WIS CD manual since I want to understand what I do (I will take some time to digest the information I got here too). Unfortunately I had bad experience with both dealerships, independents, tire shops etc. Doing my own repairs, I learn a lot, save (big!) money and will have a nicely running car.
Just one bad indy experience for illustration: my car cut off in the middle of the run. I had it towed to a recommended independent specialized in MB and BMW. It turned out to be the rotor, distributor and OVP. Those are standard items to check in such conditions as I learned later from this forum. I got a bill of 850$ of which 4.5 hrs were for diagnosis only. I have more examples of this kind (I may attract bad luck, who knows), bottomline is I prefer to do my own repairs whenever possible.
Bruno