Supposedly they are going to add "special" cosmetics to drops for finishing Strongholds at some point soon. Other than that, I would only waste the coin on Masterwork materials....and even then its so hideously expensive(5000 coin per 1 resource) its not worth it. I wouldn't waste coin on any of the crafting materials.
so currently no cosmetic items at all through loot drops or treasure chests?...everything is through the in-game store?...in the beta there were a lot of cosmetic items available which made me think they would be easier to obtain