I recently did the brake job on my MB (W140) The dealer wanted $1150
to do new pads, rotors, and sensors all around. I purchased the stuff and managed to keep my cost under $450.
I took my time doing them and made sure all is OK. I don't trust the dealer no more. But about turning the rotors, I have read many times that the MB rotors can't be turned, they are made of a softer metal than conventional brakes to give them lighter weight and they wear with the pads to give a much smoother surface, which helps you stop better. The car is well engineered, I found it easier to do brakes on the MB than on all of my other cars I owned in my lifetime. I am young but I owned a few, however this is my first Benz