Erebuni sucks....strictly because Fibreglass bodykits are generally low quality. They take a lot of time for the bodyshop to get smooth and you have to fabricate mounts. Not to mention that if you scrape it or hit it you can crack the paint easily.
For a quality AMG knockoff, I would try
www.nrauto.com. They have AMG replicas that are plastic versus Fibreglass, and I was quoted about $500 for the front bumper, minus fogs. For the 500e stuff you have to upgrade the fenders with the bumper, definately an option, but expensive unless you happen to find a wrecking yard that has one and will let parts go cheep.
These cars look awesome with just the AMG front bumper and stock rear bumper and rocker panels. Check out zorroamg's 300e
http://homepage.mac.com/zorroamg1/PhotoAlbum2.html
Scott