If all you doing is scrypt mining, just about any old 12v power supply you have lying around will probably work. Max draw overclocked is around 10 watts, so even a 1 amp supply should work. I'm using an old microscope power supply that's 12v 3 amps and have had zero issues scrypt mining with an overclocked gridseed.
So if you're like me and just want to run a single one for testing just dig around your old electronics drawer/box. Just make sure it's (-)----(*----(+) and not (+)----(*----(-).

EDIT: I ordered mine from ZoomHash. They said it would ship on the 9th and it did. Arrived earlier today, set it up, and has been running ever since without issue. The only quirk I noticed so far is that if you want to switch what you're mining, it seems you can't just stop the miner and start it again. You need to disconnect then reconnect the USB cable. This is likely a software issue (driver or miner).