Bluefins keep their own store of these for so-called diplomatic purposes. I suppose I could use one myself if I wanted to go through the SodaDeeps...
The ArchebellochTradingCompany uses these heavily in the TrenchUnder manufactory and hub.
Be careful of knock offs dearies. A few of these helms sold in MisthomeIsland are of dubious quality, granted you'll only find that out until it's too late.
Saving a fool who bought one of these was how I met my first husband. That being said, such purchases rarely result in Selkie brides.
--by GithsemeTyar