Here's an aftermarket unpainted polyurethane bumper cover that's within the realm of reality price-wise compared to a dealership price...
http://www.ricekiller.com/forums/showthread.php?t=96291
You may be looking for a long time to find a painted silver one (and your particular variety of silver) that's not selling for the retail cost of buying this plus the trim parts.
LA Dismantlers probably has one or will have one sooner or later, but if history serves as any indication of future or current pricing, they are as proud of their used pieces as the dealers are for new ones ordered from Germany. I've never bought from them because of this.
Oklahoma Foreign is another place to check. They're less greedy, but still not cheap.
Hope this helps!