Servicing - Main Dealer or Merc Specialist?

Also what sort of costs are we looking at for a service from main dealer and from a specialist.

I have a Merc C200 cdi se coupe.

 

If you know of a Mercedes specialist try them first, I've always found them to be a couple hundred dollars cheaper. I only goto the D(S)ealer when the Mercedes specialist can't fix it. I've even had the transmission rebuilt by an transmission shop for cheaper than what the dealer was asking.