You can purchase MELON from these places
Go to Bittrex
Bittrex is one of the larger crypto to crypto exchanges offerign a large number of trading pairs into bitcoin - including all the major cryptos such as darkcoin, nextcoin and litecoin
Go to Kraken
Buy, sell and margin trade Bitcoin (BTC) and Etherum (ETH) in exchange with EUR, USD, CAD, GBP, and JPY.
Go to Livecoin
Go to Liqui