I replaced front and rear windshield seals and all the door seals with OEM and they were not much more that after market ones.

Hint; replace the 4 tubes that go from your door frame to the doors. The carry the vacuum tubes and the electrics to the door. They tend to leak and will fill your floor boards with water. They aren't really cheap but constant water in your foot wells can be a bit costly after a while.

Hint; Check out the door window slides. They tend to come apart and bind up the window. MB slides are really not cheap and I think after market ones will be just as good.

Hint; When you replace the windshield seals ask around at window shops to see in they actually know how install theses windows. Get them to tell you how they do it. Most will BS you just to get the business but in reality haven't got a clue. It is a tricky process, takes 2 men, and you can crack a window before you know it.

If your window has an aluminum frame around it the frame MUST go on the window BEFORE the window goes in the car. Then you wrap a rope around the lip of the seal that goes inside the car, set the window in place, push it in as best you can, make sure the inside lip is inside the frame, and then pull the rope out. Sounds a bit tricky and it is. I have been involved with 3 replacements but only helped the window guy. I didn't try it myself.

If you are going to replace the windshield seals think about installing a new headliner if you need one. On my 115 the windshields must come out before you can get in the headliner.

Hint; Ask your MB parts man if you can buy parts at a dealer's discount. Call yourself XYZ Restorers and see what he can do for you. I did this and saved a bundle.