Steering Damper should be changed every 60k... it's only about $30 and 15 minutes labor.
Lower control arm bushings usually last 100k miles or so. Did you ever hear any popping sounds? Was the steering more squarrely? One way for sure to tell is... did you notice how much tighter the car felt when you got it back from the repairs?
For my lower control arm bushings, I was charged $450 TOTAL, parts AND labor, at my mercedes dealership. I think anything over 500 is unreasonable for this. If you are mechanically inclined, I suggest you change the steering shock yourself, it's SO EASY!!!
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)