Here's another source for fans:
http://www.nexfan.com/casefans.html

I used an old laptop power supply; we have tons of them here at work. Just spliced into the DC side. With most of these fans, you can also supply them with lower voltage, just make sure your power supply has enough current. They will turn slower, but still move air. I'll plug it into my Onkyo's (A/V receiver) switched AC outlet & be done with it. Onkyos tend to run hot and I don't have much headroom above the receiver.