The latest episodes are not on Amazon or iTunes (or DVD). Just searched for Game of Thrones season 4 on Amazon and iTunes to confirm.
HBO's business model is exclusivity, which in my opinion is anti-consumer.
HBO's business model is exclusivity, which in my opinion is anti-consumer.
Then don't watch.
If everyone without an HBO subscription refused to watch GOT then HBO might actually be inclined to re-examine their subscription options.
Market pressure is already pushing HBO towards a non-cable option, they're just moving into it kicking and screaming because the current way has been immensely profitable for them.