As it is right now, it's really hard to get a hold of the Helm you're looking for, it's 30+ possibilities from that Box, and most people don't really care about ep 18.1 gear or content, so even on the market, it's hard to find what you're looking for because nobody cares about doing the dailies and farming the amethyst fragments.
My suggestions are:
1) Create an NPC that sells all Helm of Faith available, the price could be something between 1500~3000 Amethyst Fragments, I think it would be fair, considering the amount you get per character daily.
If it's too much work to set up an NPC, then:
2) Lower the price of the Helm of Faith Box to 100 Amethyst Fragments.
