My naturally aspirated roadster failed state inspection because the rear lower knuckle bushings clunked a little. My local repair shop, whom I trust, said they had to do a little research. They just called me and said that the cost to replace the 2 rear lower knuckle bushings is $700.00. The mopar bushings 68071135AA list for $130 each but are on the internet for $100 each. Does this seem like a reasonable cost with labor or is my local shop asking to much because they have not done this job before? I called Moog suspension parts and they told me that the crossfire does not have the same bushings as the 2003 SLK320 and that Moog does not make them for the crossfire. I did find MTC bushings that supposedly will fit the MB or the Crossfire for $12 each with shipping on ebay. I also worry how long they would last given the $500 labor cost and the likelihood that they are made in China. Should I look for another installer? And no I live in the middle of NH which is the same as the middle of nowhere so there are no shops specializing in MB that I know of within 100 miles.

Anyone willing to offer any advice? Also anyone else had this part fail? I have just under 100K miles on the car.

 

There are two suspension links that connect to the lower part of the rear knuckle. The control arm ( it is the larger of the two ) and the track arm. The track arm runs forward and aft. The control arm is inboard and outboard.
Both are the same as that which is run on the Mercedes 2003 SLK 320. The parts are interchangeable. A brand new lower control arm will cost about $75.It will come with a new inner bushing installed, but the outer bushing which is pressed into the knuckle would still be original. So sounds like you want to change out the outer bushing.
The outer bushing for the control arm cost about $20 each. You seem to think that is the problem . So two of them, one for each side will cost about $40 brand new. Removing the old bushing and installing the new is a job that will more than likely require a press. The outer bushing is pressed into the knuckle. These bushings on the lower control arm are really soft compared to others on the suspension links.
The track bar can be bought brand new for about $34. So one for each side of the car is $68. A new track bar will have new bushings installed. So the old track bar simply needs to be removed and the new installed. That is an easy job.
Very few have found it necessary to change the outer bushing on the rear control arm. You may want to ask your mechanic for his opinion as to whether there really is a problem there which needs correcting.