If the tie rods, ball joints, etc aren't worn out then an alignment tech will turn some nuts on the tie rods or adjust an eccentric bolt on the control arm to get the alignment correct. The alignment shop I use charges a fix rate for a front alignment - about $40. A front and rear alignment is about $47 if the car is capable of being adjusted in the rear. They only charge about $10 for the inspection if there are worn parts and they can't adjust it.
In our small city the MB dealer doesn't do their own alignments. They use a local alignment shop. I take my car directly there and avoid the markup. I usually ask for the first appointment of the day at 0700 and wait for the car to be finished. Takes about 35 minutes.
Give a couple of places a call and ask about their experience with Mercedes.
1984 300D Euro