Maybe this product has been found and discussed, but I wanted to throw it out there in case anyone is heading this direction.
modifies a window AC unit for use as a refrigeration device.
$300 for the temp controller. Available on ebay or from the site.
I have not started reading threads on this type of build yet, as I am not quite there yet, so I apologize if I am rehashing information. I ran across this doing some sourcing for equipment for work.