Actually the main reason price is so high is due to the supply, not of the items, but gold, since the removal of the previous gold based elixir system, there has been practically no gold removed from the game, even with guilds it's probably quite easy to have someone buy it for plat for u and u pay them less than the stores 250k. I remember at the 50 cap I believe the most pricey thing(I joined around december 2010) was the vyx helm and Jacobs helms which were 400-500k
Sewer cap got items generally around 1m for top quality items, 51 fury shield and raid recurve were the most I think. That cap was when the plat elixirs were added, but many of the hardcore players had arleady capped with gold elixirs. The demonic sets brought the huge change, I barely played that cap, but sets were over 10 mil for awhile I believe.
These last too caps have introduce much more easily obtainable sets, but the prices were still around 1 mil an item.
Dragon sets are actually rare, and have a high demand however, which allows the terrible shape of PLs economy to be revealed.