I reckon that requires a bit of explanation.

Why don't sellers simply start listings at the minimum price they'd accept? I avoid listings with a reserve price.

Does that imply the K-01 isn't?

Isn't the GRiii a bit like a Pentax K-01 but with a fixed lens?

Number plate definitely NOT illegal. The white/yellow reflective plates didn't come in until 1968 !
Those front number plates were considered potentially dangerous and were no longer required as from August 1975. however there was no legal requirement to remove them if already fitted.

Try a camera shop somewhere and see if they have something suitable in their clearance or S/H bin.
You don't actually need the circular variety for Pentax cameras though if shared with other brands you might do.

This might be worth a punt: https://www.ebay.co.uk/itm/62mm-Genuine-HOYA-Circular-Polarizer-Filter-CIR-PL-CP...

Surely not compete against it, just embrace it as well. Perhaps in partnership with another company similar to the MX-1 tie up with Olympus, sharing the basic deign, or as with Samsung using the K10/K20 body for their GX10/20. Aren't the main Ricoh cameras that type of camera anyhow reserving the DSLR range for the Pentax brand. Perhaps a decent Ricoh mirrorless EVF fully supporting K mount lenses is called for which would maintain Ricoh's policy when they bought the Pentax brand.
Ricoh have already used the K mount for film SLRs, albeit with the dreaded extra pin.

Addendum: elsewhere I've spotted that the case should be HD-100.
If you spot one without the case grab it anyhow as you may have along wait for the next one to come along.

Do I?
I cannot see Ricoh listed as a participant at IFA2019, but then I cannot see Canikon listed either, though Sony get a mention.
It isn't really a photograhic show. more of a European CES, ie general tech event for TVs,PCs & phones etc.

So who will be hosting the new Ricoh/Pentax products at IFA then that I should know about? The OP asked about new ones!

Perhaps Ricoh are donating one of the new mugs to every stand there!

First off welcome to PU.
That's a very scarce lens. There's several on eBay in Japan. The case for it is HA-90B