Yeah, interesting choice of materials for sure, though it helps explain the $500+ sticker price on them..well a little at least.
You can get a 3x4 panel of (non-crimped) aluminum wire mesh for about $75; also check MSC, you can buy smaller quantities versus the site linked above. You should be able to get at least 2 grilles out of one panel if you want to stick with the same orientation of the squares. I think I'm going to go with aluminum, as it will be lighter, cheaper to replace, and likely easier to work with.
As far as the Shelby link..hard to say exactly what they're selling. Almost sounds like it's something that goes on top of a stock grille or something, but I'd say you best bet is to give them a call for some clarification.