This has been discussed many a time in the tech forum - search the archives for more discussion than you'll want to read. The part itself is ~$1.25, though that's dealer pricing - you can save almost half mail order!
Installation is more frustrating than difficult. The bushing just pushes into place - but the pushing is a real bear. The archives contain some description of homemade tools used to do the job.
I've done this a couple of times on a couple of different cars. It never requires more than a few simple tools, never takes too long, and always makes a nice difference. In fact, my '98 E-class needs this done right now - I've been driving around with the bushing in the ashtray for a few weeks now. Maybe I'll head home early and take care of it.