Herschel Walkers Brain escaped

depends where u are.

industrial / agricultural tubs can be found cheaply but might need super intense cleaning.

lazy spa pumps / heaters can be found used on ebay/ CL. loads of ppl are careless with the inflatable envelopes of their lazy spa and sell the pump/heater units afterwards.

minimal effort/ great value for money.

biggest issue, potentially structural depending where u place the tub. water is HEAVY