FWIW, Everything I have gotten from that site has been OEM. They specify if it's not. Even the CPS I received was a Bosch and it was only $45.

Another site with gaskets and good prices (on all but the VCs):
2002 MERCEDES-BENZ SLK32 AMG Parts - OE Discount Parts

The nice thing about that 2nd site is they give Parts Breakdowns to help identify your part.

I know you are in a time crunch and getting them from the dealer, but figured I'd add some info here in case you need stuff in the future.