The stainless steel overlays used to be on eBay all the time. I don't recall seeing them for long time now.
The cover that looks like this but is plug-n-play would come from an SLK.
The covers in the pics look like the 2 piece version. You will need the airbox, and front engine cover(for a v6). The same airbox is used on the v6 and v8 with different engine covers on the front.
I think this is the airbox you will need:
2003 Mercedes Benz C240 Airbox Cleaner Assembly 112 090 15 01 | eBay
Here is the v6 engine cover that took me a while to find for my car:
01 04 Mercedes C320 Engine Cover Nose Piece 1120100467 NL0028 | eBay
Others will chime in for a perfect fit with the correct part number.
James