The only thing I comment on about tubs is they are an absolute nightmare to control the ambient and cool end temps in cool rooms. They are very very poor at holding any heat and typically will have ambient and cool end temps that are the same as the room temp. They should be 80ºF so it depends on what you call expensive if heating a room to 80 year round is expensive than tubs are on the top of the list. Custom enclosures run about 200$ for an appropriate size and can be easily set up to self heat the cool end temps to a degree it might cost less in power in the long run.