Common problem on that car. The above info is right, in that you're going to be at least $2K light if MB chips in, probably $3.5K or better if you're on your own.
They started with the AC evaporator on a CAD drawing, and then designed the remainder of the car around it. It's a hulluva tough job and requires removing most of the front interior of the car.
1998 C230 "Black Betty"