Geez, the prices of store bought coolers are nuts. And, they are WAY more complicated than most of us need. I worked at a place in the past that ran welds on 1/2 aluminum 24/7 and all that old miller transformer had for a cooler was a 10 gal tank and a small gear pump. The coolant never got more than bathwater warm. There was enough surface area on the metal tank to cool the water thru convection.
So, until I make one like I just described I am using a $13 setup. Go to Harbor freight and buy their $13 submersible water pump ( http://www.harborfreight.com/200-gph-su ... 68372.html ), borrow your wife's stock pot (capacity 2-3 gals) Don't get fancy, just electrical tape the hose to the pump, drop it in and fill pot with water and plug it in to the electrical outlet.
There ya have it, all your water cooled gun needs, a steady flow of water. Just keep the water clean and topped off. Now you have time to build/buy one as fancy (or not) as you want.
The only real drawback the pump has is a lack of pressure. It works great at the level of a workbench but if you are welding above your head or higher you might need a more powerful pump.
Errr, one more thing. Clamp the return hose inside the pot. Or yer gonna have a wet floor like me.
