There is number of special currencies and relevant shops:
Two arenas shops, guild shop, crucible wagon, tree and arsenal.
In all of them (except tree) there are items sold on second page.
Now question: does anyone buy these items for outrageous prices there? (Except arcenal as there are no soulstones but much more special coins)
Even if I use in game economic:
5 soulstones = 500 special coins = 20000 gold sell equivalent (or 100'000 gold buy equivalent) = 200 diamonds (5$) = 400 (2000) gold per one coin
Warrior gloves (lvl23 item) = 513 special coins = 746 gold sell (or about 3500 gold buy) = ~1.5 (7.5) gold per coin. If I buy 200 diamonds and use midas it will give me somewhat equivalent of 0.1$ for these gloves.
Other items will have similar cost comparison.
7000+ coins for one purple item? Equivalent of 70$ = ~7000 diamonds = 7 of same purple items in black market. Must be kidding.
It's ignoring fact that all items can be obtained via other game means, while some soulstones ONLY is these shops.
What all this long calc about? Items in special shop should be at least 10 times cheaper even to start thinking of buying them.
10 times cheaper.
Maybe somebody from older players can share different opinion.