Kevin,
I recently had the "B" service done to my ML320, and it cost $230. Since I notice that you are from the D.C. area, why not drive to Benson (MB dealer)in Annapolis and try them out and still saves a bundle. If you do not want to wait for the car, they will even give you a rental for free for as long as you leave your car with them. They have been doing good work for me. Heck, I bought two Benz from them.

95 R129
98 ML320