Last time I had the studs replaced on the front of my car I took the front hubs out and had Pep Boys press out the old ones and install new ones. I think the labor charge was $40 or so, total.

That was about 10 years ago.

Within the last 8 years I did the rear myself. I took off the caliper and rotors and used a sledge hammer to gently knock the studs out. I hit the studs by swinging the hammer only two or three inches away from the studs. Took about 3-4 blows per stud. I then fitted in a new stud and put 5 washers around it. I then threaded a lug nut on the stud and used my 1/2 inch impact to pull it into place. This only took about 15 minutes per wheel and worked well for me.
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If it needs to be maintained, repaired or replaced on a 1990 240, I've probably done it. '90 240DL, 245K looking forward to 300K badge. >>You haven't really worked on a car until you draw blood<< :-}