Take the cost of how much it would take to replace or rebuild an American or Japanese transmission and add $1500 to it. I'm not kidding. Also, Mercedes Benz mechanics prefer that you only go to them and not to anyone else. They tend to frown on knowing if a car was taken to some general auto repair shop. You're looking about $2,700 just for the transmission itself. Tack on another $400 or more for labor. If you look online you'll find one. That price should also include a rebuilt torque converter.