@triceratops That's what I was thinking, too. Gonna be hard to just come across a set unless someone has a trashed cabinet pair or just likes parting things out. They wouldn't be the hardest things ever to make as they only have 6 contact points to the speaker. I build a set of grills years ago for a pair of JBL L100T's based on dimensions I gathered from others and they turned out great and were quite an interesting build. Had to do the same thing with a pair of Infinity RSIIIb's that had broken particle board framed grills. But I guess having spent 25 years in home/car audio/video and doing custom & high end installs for both made it easier to do those things.
One place you might try calling is Speakerworks in Tulsa, OK and see if they are still building grills and if they would be able to do those. It shows they are still doing grills but not sure for what kind. I know Dave did many for JBL.