The Swiss Quality Exchange for purchasing crypto directly via Credit Card or Bank Transfer. You can also use your existing crypto (BTC, ETH, LTC etc) to purchase HVN. It has a lovely clean interface and great customer service, read more good stuff about it here
. (Exchange not yet available in the USA)
HitBTC is one of the largets crypto exchanges out there, offering a wide variety of currency pairs. It boasts a great level of liquidity but fees on the exchange are high.
get your $HVN
IDEX is an Ethereum based decentralized smart contract exchange. If you hold Ethereum this is one of the best places to purchase $HVN.