Husband plays WoW and looking for a cheap new desktop... What do I look for?

I've seen gaming computers for close to $3k and I've seen them all the way down to $200. All we need is a computer that can handle WoW. (World of Warcraft) but I haven't the slightest clue on what to look for in a computer. Should I just get a cheap one with a good amount of memory, and add an updated vid-card? Please help someone. The hubby's getting antsy. =(