I just purchased an 1100watt unit off of amzon for about $80 and took it for a test spin. That unit had no issue heating a tub full of water to 160 degrees. It’s kitchen tub from Sam’s club that I’m guess had about 30 quarts of water in it. Insulation would have definitely helped as would a lid. If you go the cooler route, maybe you could hook up two or three of the cheaper units to run at the same time. You would need separate electrial circuits to run them without tripping a breaker, but seems well worth a try before spending thousands for the commercial stuff.