And buy $100 with credit/debit card you'll instantly have access to your btc, plus you'll get an extra $10 just because you used a referral link! After the initial btc purchase you can transfer your btc and money to gdax.com for free (by linking your coinbase account on the gdax site) where you can either sell your btc, cashout your btc, or send it to a btc address all for free (if you use a Limit buy/sell order) or 0.25% fee (opposed to coinbase's 4% fee) if you do a market buy/sell order.
