I didn’t even start at the dealer for brakes. I used Brembo Rotors and Axxis Deluxe dustless squeakless pads. The factory pads turned all four wheels black in just a few miles. I was constantly washing them to keep my Benz from looking like an unkempt mid 80s Ford Escort. I also experienced a very low service life from the factory pads and rotors. My parts came from my trusted local import parts store, Mid-State Auto Parts in Columbus, OH 614-888-3838. Jim and Bill have been providing quality parts and excellent service for more than 20 years. The rotors were roughly $200 for all four and the pads were under $150 for front and rear sets together. I didn’t have the time to do the install myself this time so I trusted my general domestic and import mechanic who charged under $200 labor. $550 got me new rotors, upgrade pads and installation. I have done ML320 brakes with a friend once before and they are very simple and straight forward if you have done that type of repair before. No special tools. I have used the Axxis pads for my import vehicles for years. They were formerly called PBR and before that Repco. The company has changed hands a few times but they still make great low dust pads.
http://www.axxisbrakes.com/ I think you will be pleased with this combination for performance and price.
P.S. the frot sensor comes with the pads but the rear sensor is seperate and about $10 if needed.