Matt,
Check around the house and see if you have a 12v 1amp power supply or even just a 12v hobby battery.
I dont know about you, but I save any power adapter I find, even on old stuff I throw out. So chances are, if you have some laying around, you may have what you need.
Look for an adapter that has 12-16v output and a minimum of 1amp (1000mA). Then you can cut the end off and just splice a power cable right to it. You will need to check the polarity on the wires.
If not, here is one I have recommended before:
12v 2A PS from Digikey.com ,
$19. Or just stop by Radio Shack or even WalMart and you should be able to come up with something that will work
Good Luck,
Robert