The windshield is glued on with a caulk like adhesive.

$250 to $300 is about the market. I have had it done twice on W124's in my driveway. Important that the guy doing the Removal and Installation is familiar with MB. They need to have some spare clips for the roof rails.
If they break one, you don't want some monkey to start gluing them back in place.

Call the MB dealer and ask who they use.

Steve