You might want to contact Dave Hendy. He is in the Parts forum and can probably help. I bought one (used) from him and I think it was under $100
there is another item that you might look at. It is attached to the back of the instrument cluster and interfaces with the CCU. It is a hall effect speed sensor. The part number was 007 542 29 17 I think the Cruise/idle control is 124 545 55 32 My car is a '93 300CE and I assume the parts are common.
Anziani
'93 300CE 200K
'95 E420 122K