It's
FREE. It's out of Beta now.
Make an account and download it.
http://worldoftanks.com/Tip: After you make an account. Login, then use the drop-down menu by your login name at the top right corner of the screen, hit Activate Bonus Code, and type in NEWYEARNA. You'll get a free Tier 2 Russian tank(and space for it).
You don't have to buy gold. You just are limited to 2 tanks in your platoon, instead of 3, and gain research, and credits, at a slower rate, than if you pony up for gold. I play with guys who don't have premium accounts. We use a friend's Teamspeak server and have a great time.
Give me your in-game name and I can always add you as a friend.
“Let me never fall into the vulgar mistake of dreaming that I am persecuted whenever I am contradicted.” ― Ralph Waldo Emerson