Here is one:

MERCEDES-BENZ C CLK E SLK engine airbox cover OEM | eBay

Typically you won't use the OEM tubes since they are not a direct fit. Most go with TVT tubes to finish off the install.

The following auction will get you by until a front cover can be found. They come up from time to time:

http://cgi.ebay.com/ebaymotors/CL500...item483f974763