The center link OR drag link takes about 0.6hr to replace & possibly a special tool will be needed to loosen the tapered ends from the idler arm & pittman arm.
You also should have the front end alignment checked!
The part number should be 124-460-08-05 & list is $81. Add $40 for labor & alignment at $80-100 and you get $200.-225.
Seems that you tech is close to this figure. BUY only an OE Mercedes part OR one from Lemfoerder(oe mfr). All others are CHEAP knock offs!
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)