I just got my homebrew kit on x-mas(2006),so sorry if this thread is a little outdated. my first brew is an octoberfest lagger, antd i live in an appartment, therefore i dont have a cool basement or a lot of money to buy a specialized cooler so here is what i did. i took the box that my kit came in and turned it into an insulated cooler.
I cut one side of the box along the bottom, one side,and the top to make a door. than i cut a square hoe in the back of the box the same size as a 12volt compuer cooling fan that i had. made a square cardboard tube that connected the fan to a cardboard sill plate that ran across the bottom of my window( i made the sill plate as long as my window so that i could close my window on it and seal the outside air from getting into my warm appartment). this provided a cold air supply into my "chill box", but i found that without a vent for the warmer air to excape, the system wouldn't work right. i used a couple of paper towel rolls to vent the box. I cut a hole in the very top of the back side of the box and ran the tube down to the sill plate. i figure hot air rises, so let's force the hot air out first. anyway, the fan is connected to a thermostat from a small elecric heater. unfortunately, this thermostat was designed to turn somthing "on" if the temperature was too low, and turn somthing "off" if the temperature was too high. this was exactly opposite of how i needed to controll my fan. the solution was to power this fan off of a 5 pole automotive relay thus reversing the function of the thermostat. the whole thing is powered of of a 12 volt power supply inverter that plugs into the wall. i figure as long as the outside temperature is below 45 it should work o.k. this is the second day of my fermentation and i've held a steady 53 degree temp in the box. this system didnt cost me anything to build because i had most of the parts lying arround. one more thing, i noticed the fan was running alot longer than it wasn't running. i figured it was because my appatment was warming the box too much. I insulated the box with a layer of black garbage bag and 2 beach towels and it dosent seem to short cycle as badly. anyway gotta go figure out how to brew lager in the summer.its allready january!