The expenses related just to the glycol system were
additional freezer (serves double duty with frozen food), $200
trunk line, 20-ft $350
pond pump for the gycol. $ 30
propylene glycol, 2 gal $ 20
wood collar on freezer $ 40
So that's $540, but since we keep a lot of frozen food in the freezer, that $200 shouldn't really count.
With my small glycol reservoir, the glycol doesn't have much residence time, so I get a temperature much higher than the freezer temperature. If I wanted a lower glycol temperature, I would just use a bigger bucket and more glycol.