You can purchase CUBE from these places
Go to IDEX
IDEX is the only Ethereum decentralized exchange with real-time trading and high transaction throughput.
Go to Bithumb
Bithumb is one of the largest exchanges in South Korea, allowing users to buy/sell/store Bitcoin and Ethereum.
Go to HitBTC
The most advanced cryptocurrency exchange to buy and sell Bitcoin, Ethereum, Litecoin, Monero, ZCash, DigitalNote, Ardor.
Go to OkEx