Look up good WOW private servers. All you need is the game, and you can play for free on a server not hosted by the WOW company. And yes there is always tons of people on them.
Also private servers offer so much more then the normal WOW company hosted servers. Custom shops, better drops, you name it, and you can probably find a server who has it. You can even do normal servers like the WOW company hosted ones. I was on one once that got you to level 70 after killing 1 creature from the spawn, and every little thing sold you 500 gold. They also had custom shops where you could buy the best crap in the game for like 1 copper each.
But I wouldn't get into WOW myself, it's gay in my opinion.