I actually discovered that I am able to pay HBO for Game of Thrones. HBO decided to air GoT here in Brazil simultaneously with USA. I called my television provider, added HBO for R$ 30,00/mo (around $15.00) and after the end of the season 2 I just called there and removed HBO again. I am planning to do the same for season 3. Is it so hard for people around the world to do the same? (real question, not being sarcastic)
You're ignoring the cost of the cable subscription in the first place (unless your 'television provider' is the government and you don't pay anything).
Well, this season of GoT was 9 episodes. If you wanted HBO over the whole run so you could watch them live - you would need it for 3 months. However, if you're willing to hold off until last month, you could get by with waiting for the last episode to come out, buy one month, watch all episodes, then cancel.