Add mahirim tails to the store.
Long tails,short tails, fuzzy tails, bushy tails, stumpy tails.
Im joking but I'm not. You could add tons of cosmetics for other races as well.
Anything that lets players customize their characters aesthetic without being obscenely expensive will sell like gangbusters.
I would also add MOST of the cosmetic dyes on the store which would effectively set a price standard for them with gold. Save a few dye colors for world boss/dungeon boss/faction pvp reward when it comes out.