There are multiple Mercedes (AMG) style dead pedals on ebay. I purchased the one that ships from Australia for $40.00. I feel it's the best match. Looks like OEM fit and finish. Other options range from $19.00 and up.

Mercedes AMG Dead Pedal Footrest A45 C63 CLA45 GLA45 W204 W164 X156 C117 | eBay


Check it out.