Coins can be used to purchase things from the in game /cosmetics menu including treasure chests, gadgets, mounts, pets, morphs, miniatures, banners, balloons particle effects and more! Note: Some rarer things can only be found in treasure chests such as the ender dragon mount. 

10,000x Coins
9.99 USD
Buy
50,000x Coins
39.99 USD
Buy
100,000x Coins
69.99 USD
Buy