I also have a headlight lens that recently got a rock chip and needs to be replaced. 93 400SEL. I have not checked with the dealer yet, but are you serious? They will not sell you just the glass lens part separately?
The lens assy. is around $300-400 I think!
Removing the turn signal lenses is pretty easy. I think there was a diagram in the box when I put in the aftermarket clear lenses, its pretty easy.