Auto Body Specialties has the best price I've found at $127. I called them and asked a bunch of questions. Here's what I was told.
They are 18-19 Gauge metal. They are made in Taiwan by a company called Key Parts (spelling?). ABS commissioned them 10 years ago and had a 1 year exclusive. Now Key Parts makes them for everybody including Sherman and Goodmark.
The guy I talked to said he had personally checked the fit against a stock quarter panel and they fit well.
ABS ships UPS from Connecticut. Shipping to my zip code in CA would be $49.