Here's the prices realized from the latest Chip Chat auction -- there's 8 chips that realized $1000+ each.
If you set your high-end threshold at $400-$500 each, there's probably triple that amount.
As one example a Z-3 chip I was interested in (but didn't win!) did indeed go for a Z-3 price range (including buyer's premium). I didn't check others, but would not be surprised if "full value" was attained on the best ones. Of course, there's the "Doug dust" factor too ...
IMO, the truly rare chips out there are holding up pretty well, even if they don't change hands that often. It's the "scarce but available" range of chips that need to be priced right in order to attract buyers. ... But it varies widely with they myriad different types of chips out there.
Just my humble opinion.