In case anyone is interested: mercedes sells an OEM E-class avantgarde like grill that fits the C class grill frame by the following part#: B6 88 01 27 . This part# includes the black shiny grating and the chrome trims and I am being told that the US dealer wants to have 270USD for this part (220USD in the Netherlands).
It is more expensive as the Becker equivalent, but it is OEM mercedes (which doesn't mean that it is necessarily of a better quality).

greetingz,

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1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)