The AMG AERO's I wear are out of Production/No longer available. I did see a set on EBAY a few month ago go for ~$1000. The tires in 235X45X17 run anywhere from $100(Kumho) to $270(Mich.Pilot Sport) ea, depending on the manufacturer.
As for all the 500E Parts, the Fenders,Hood,Headlights,Side valences,Fog lights, bumber cover etc. all came from the dealer(with MBCA discount of course). I did roll the fenders in the rear, but not necessary in the front due to their being 500E spec.