Oh, look, a second post. Thank goat's momma for the pointer.
You'd need a 12v supply capable of 60watts output... around 5amps. Just about any old computer power supply can push that, many laptop supplies can and they're dime-a-dozen-ish at surplus places. (battery power alone won't do the job, its gonna pull 5 amps or so at startup)
You'd also need thermal paste but not anything expensive... standard zinc oxide ointment from local drug store will do the job.
The other thing you'll need: Fan and heatsink from a computer processor. New these can run a fair bit of money but generally some guy near you will have one to spare and may be willing to help set up the whole thing for a wink and a hug.
The peltier unit needs to be wired up to a molex-D (the four pin connectors used by older hard drives) so you can hook it into the power supply of a computer or wired to the connector used for the laptop external supply.
Troublesome bit... aluminum stock plate. You can't just put the peltier up against the tank wall, you actually need to spread the cooling out some, so you're looking at a seven inch long by three inch wide piece of stock about 1/8th an inch thick.
You just zinc the peltier to the flat on one end of the stock, zinc the heatsink+fan on the other side of the peltier then clamp it together (two pieces of coat hanger wire, one through the heatsink and the other on the back of the stock bar that then have their ends twisted together for about an inch outside each side should be enough, your computery friend probably has a good idea or some parts that will work as well, two bolts and some strapping, etc) then hook up the fan and the pelt to the power supply and click! Cold metal stock bar.
Aluminum is great at transferring heat in low gradient situations but you'll probably want to coat the portion you stick in water in some kind of epoxy type paint or wrap it with a tight layer of saran wrap and practice those christmass/birthday wrapping skills. so water can't get to it.
Maybe $30.00 and you're chilling water.
That web page has stronger peltier units for those of you with engineering majors.
You can also heat tanks this way but you'd need some kind of thermostat. I'm considering the 100 degree temps being the regulator for its cooling power.
Remember to put the power supply running it someplace safe from the water... if it cools too well you can try disconnecting the fan, the peltier won't mind.
(a reference article!: http://www.aquariumadvice.com/forums...ube-94972.html