I was looking around for places that offer good custom license plate frames... found this one shop that uses black anodized aluminum frames. They weigh 3 ounces and are nice and rigid.

The cost $16.99 each plus $5.99 if you want it customized.

http://www.autoxpressions.com/blacanalfram.html

I just ordered mine, I'll let ya know the quality when it arrives.

Total with priority shipping ($7.50 is kind of expensive, but whatever, the plate is way cheaper than anywhere else) was $30.48