I got 42K on the original pads F/R. I am replacing them with EBC reds today. DIY.

 

I used to be an auto mechanic many years ago and I still work on my won vehicles. Recently my sister in law asked me to check the brakes on her 2006, C230 because the Brake ware light has come on. The sensor on the pads, once the friction material wares enough to allow the face of the sensor make contact with the brake rotor, it causes the computer to activate the Brake Ware warning. We bought the better grade brake pads from a local auto parts store and paid about $85 (front pads) I was able to reuse the sensors since she did not drive the car to long after the warning came on and I also had the rotors resurfaced for a new fresh friction surface ($15 each done at a local auto parts store)
I suggest you call the local dealer and at least 3 local auto parts store (I always shop for best price making sure I do not compromise part quality) and you can have an idea of how much the pars should cost and judge by the difference how much they are really charging you for labor. It took me about 45 minutes per wheel and I do not do this for a leaving any longer so I am rusty. My local dealer charges $95 per hour labor.
I still have not been able to figure out how to reset the brake ware warning so if anyone can help I appreciated. Good luck, Jairo