How much does Warcraft cost
If you're talking about Warcraft 1, you could probably snag a copy off of Ebay for no more than a couple of US dollars, but I assume you mean how much does World of Warcraft cost to play? I'll answer that in the order it would matter to a new player.
There are free 10 day trials you can use, which have limited communication because of people creating new accounts and advertising gold-selling. A currently playing friend can use a special e-mail invitation (again a 10 day trail) that allows you to earn triple experience whenever they have a character of a level close to your character's near by, as well as the ability to summon each other so long as your characters are both on e/o's friend lists. This triple experience and summoning ability lasts 90 real-life days after you create your account, whether or not you're able to play during those days or not.
The key for the original version of the game costs $19.99 USD, and the upgrade to a full fledged account comes with one free month of gameplay. All prepaid game time (including the limited abilities of the 10 day trial I'm afraid) stacks end to end so you don't need to worry about waiting for your time to expire to add more.
There are four ways of paying for your account after your free month has expired, and three of them are based on a Subscription. Thee three options are: a month-to-month package at $14.99 per month, a three-month plan at $13.99 per month, and a six-month plan at $12.99 per month. The subscription fees for the three-month plan and the six-month plan must be paid in full. There is also a retail pre-paid time card for two months that costs 14.99 per month.
There are two expansion packs currently, and one that will arrive on December 7th, 2010. Each expansion will take time for you to level up enough to need to buy it to keep progressing, so it isn't a whole lot of cost just to start playing. That being said, almost nobody does the original endgame content anymore, since they're past it, so it's practically a necessity to buy them once you're high level enough to handle them. The first one costs $29.99, but there is the option to buy the Battle Pack, which includes the regular game as well as the first expansion, for $39.99.
The second expansion currently costs $39.99, but with the upcoming third expansion some people think there might be a drop in price soon.
The third expansion will cost $39.99, and will allow you to access every part of the game so far. The game is always being patched to balance out play and to add new content, so don't worry about waiting for a long time between expansions.
Aside from the 10 day trials and that first free month, there are two ways of earning free game time. They are Recruit-A-Friend and the Scroll of Resurrection.
With recruit-a-friend, you can invite others to the game and reap the same benefit of triple-experience you did earlier, though you must remember that you must be near their level and close to them to earn it. This is done to encourage you to help out the player you invited to the game instead of just inviting them and then forgetting about them. That's not the half of it though. When your friend upgrades to a full account and
pays for his first month (that's in addition to the free month), you earn a free month of play time yourself. When your friend pays for a second month, you earn a fast, two seated Flying Mount. And no, that isn't common when you get to the end of the game, as there is currently no other way to earn a two-seated flying mount. In fact, a two seated ground mount costs huge sums of in-game currency, and isn't nearly as useful, so it really is a coveted prize in the game. You can send out up to 20 invitations at once, and each invitation is considered null if not accepted within 30 days of being sent. It's a good idea to add each other's emails to the friends list instead of the characters, otherwise it's quite possible that you won't know when your friend is online but playing a character you don't know yet.
With the Scroll of Resurrection, you can give time by inviting a friend who hasn't played the game for a while, at least 90 days, for 10 days, and will actually give them access to the 1st expansion for those 10 days, even if they hadn't bought it. If they come back and pay for another month of game time, that month of free game time is yours. This is much harder to do than Recruit-A-Friend, as your friend must be A: willing to come back and pay for another month, B: not have the 2nd expansion pack on that account, C: your friend can only receive 3 invites, total, from both you and any other players who attempt to do so, and D: you can only send out 5 of this kind of referral at a time. If you ask me, unless the stars miraculously align, this is much more of a hassle than it's worth.
The short answer: 10 day free trail, $40 for the full game and the first expansion with a free month, $15 a month after that, $40 for the second expansion, and $40 for the third expansion.