I would answer it depends.
- some are from inaccessible locations :
.
remote areas : let's say all the rare species from New Ireland, New Britain, Choiseul, Bougainville... we know where to find them but it costs tons of dollars to go in some specific mountains (plane + guides + sometimes helicopter to reach some summits)... of course the selling price is high.
.
national parks : some Delias like
Delias maaikeae or
Delias vietnamensis pequini are known from National Parks only. So nearly impossible to collect.
.
nearly unknown areas : some flies in unexplored areas like the Delias from the Foja Mountains in Papua (only one expedition went there in the 90ies)
-
some are from easy locations but rarely shows up, they must stay in the canopy 99% of their life :
.
Delias agoranis from Thailand is a good example.
.
Delias fioretti from the Pass Valley (Papua) is another (if we consider the Pass Valley an easy location...).
-
some females are still unknown to science (
cumanau, maaikeae, laknekei...), they stay in the canopy and can't be lured or baited.
- some
Delias species are thought to be
extinct :
Delias maudei, Delias bosnikiana from Biak island.
- some
Delias species may in reality be
rare natural hybrids (
Delias nakanokeikoea)
- some are
still unknown to science. Dozens of New Guinean mounts haven't been explored yet by entomologists.
For their rarity and high popularity among collectors, a lot of
Deliasare sold above $1,000.00 per specimen and few has even reached $10,000.00.
On the Delias website, the extremely rare species in collection have a black dot next to their latin names (less than 10 specimens known) and the rare species a red dot. An example with Delias cumanau :
https://www.delias-butterflies.com/spec ... as-cumanau