I think the lucite on these pens is too clear. I have seen quite a number of offerings of Ariel Kullock clear demonstrator productions, and they don't appear aged like originals.
I think it's wonderful that some like Ariel Kullock have made the clear demonstrator replicas, giving more people the possibility of having such a reproduction pen like the originals. We needn't be so credulous, however, as to believe they are original Parker demonstrators. They are not so rare, not so valuable but you get to have the Parker demonstrator kind of experience, like people had back in the day.
I have an violet pink AK 51 fantasy aero double jewel demonstrator, and I think it's interesting, but not to be passed off as some "rare Parker demonstrator." Enough people are familiar with AK's work that that isn't likely. Those pens in the auctions went for about what they were worth, maybe.