I can't seem to find where to buy the actual game on battle.net. Is it even possible in China?

There is no need to buy the game in China. Just have the game downloaded, add some game time and you're good to go all the way up to MoP. The system in China is way better than in EU/US

Okay. Thanks. I thought it seemed strange. I read a lot about it, and thought you at least had to buy the original game, and then you'd get the rest for free.

But this is even better! Thanks a ton.