Ooh, I've never heard of these, "...reinforced plaster" mmm, no expense spared, while plaster is an excellent material for artists, the grades used commercially leave something to be desired in terms of their aesthetic appeal. Still, if the quality of that paint job was replicated in production and not just something offered up to the agency's cameras, they'd be worth looking at. I'm off to e-bay now to see If I can find some.
It seems that, that $7.50 would have been a smart investment, $800 - $1500 is the price they're getting at auction for items in rather less than mint, although nicely restored, condition.
Your comments are very welcome!