The parts are fairly reasonable about 30bucks ea. for the lower ball joints and I think about 50 or so ea. for the upper control arm/ball joint combo. These were TRW brand.
The lower joints will have to be done at a shop that does MB work...there is a special tool to press the new joint in place. The uppers you can do, but you may need a friend for a few minutes when it comes time to put it back together (mostly with putting a big bolt back in its home) The track rod mounts (I have not replaced these) looks fairly straighforward, and may be even the easiest out of the three. When I had inside wear (with incredible feathering) the uppers were at fault. One of my lowers had failed prior to the upper replacement..no tire wear involved, just noise.
I think that the biggest consumer of $$ is the time involved with the uppers, but if I had to do them again I could probably do each side in about 45 minutes if I wasn't in a hurry (which I would not recommend being in)