I got this at a University auction for $20. R12 freon and built in electro-magnetic drive pump. The reason it was up for auction was that it made a horrible noise when the pump was turned on. For $20 I didn't care. Turns out the impeller in the pump housing had a set screw that came loose, letting the impeller rub on the metal housing. Quick and simple fix, works perfect now. Love those non-technical scientists for throwing away a perfectly good machine.
Holds 4 gallons, gets down to -10C with a load on it, has 1/2" hose barbs on it already.
Score of the decade, IMO.