There are many places to buy bitcoin via internet. But if you want to buy btc from your master or Visa card at a cheap price, I think cex.io is the best place. You can buy and hold the bit coin in their e-wallet or send it to any e-wallet. You can sell your Btc and keep your $$$$ in cex.io and withdraw it to your master or visa card at any time.
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From @dwcp