Not sure how similar your system is to my 1996 C220 (W202 I think), but I paid less than $300 for full semi-metallic pads, rotors, wear sensors, and lubrication grease for all 4 brakes to DIY.
Granted, it helps, is essential, to have all the proper tools to do your own brake job.
If you are mechanically adept, I would suggest you give it a try. Not having a repair manual for my car I was very nervous about doing the brakes, but using my pat experience on my other (American) cars, I pressed on. Wouldn't you know the Mercedes brakes were MUCH easier to change out.
Even if you don't have the necessary tools, you could spend around $100 for them. This still brings you to a total cost of around $400. An afternoon of car repair is all you should need.