Tshank, My intention was to use a coolbot, but I'm choosing not to. The benefit of a coolbot, is that it is a smart controller. The coolbot has a probe which heats the temperature probe of the AC, which allows you to use a low cost window AC to get the box down into the 30's.
A regular controller simply turns the AC on and off and will only get as cold as the AC will go, before freezing up.
I found the 5,000 btu AC unit would cool my box down to 65 degrees, even on a 100 degree day without the coolbot, which was good enough for me. If you wanted to obtain and maintain the 55-58 "cellar temps", I would use the coolbot. If mid to high 60's are acceptable, then you could get by without a controller at all, or if you like to really know and control the temperature, then any controller that you can turn on/off the 110v source should work fine. I'm cheap and like to tinker, so I built my $16 controller solution.