The oem replacement pads are super quality. Stay away from the generics, you get what you pay for. A friend of mine recently had a brake job done at a "Mercedes Speacialty Shop" and two days later his brakes sounded like they were metal to metal because of the generic pads. They also reused the old rotors which is fine if you turn them [they didn't]. I picked up pads at the dealer for about $70 and new rotors for about $35 a piece from an aftermarket parts house [Brembo]. All said and done, brand new pads, rotors, and sensors for about $150 on the front. Best of all no more squeal!
MB rotors are not meant to be turned and MB actually advised against it a few years ago. They are so thin anyway that turning them will usually put you at or below the wear limit. The rotors are so cheap that you just change them when they reach the wear limit. You generally get two or three sets of pads to a set of rotors.
Linear Mode
