Botnets for the sake of DDoS cost less than a cheap lunch to rent. The more you pay, the more powerful it'll get. It most certainly isn't enough to bring down a Blizzard Server, but most definitly strong enough to bring down a guild's VT/TS server or something around that size.
It's terribly childish and very lame, especially when it hurts a lot of people who didn't do anything wrong in the first place.