If you can't afford some flexwatt and a good thermostat, digital thermometer/hygrometer, and IR thermometer (and don't have those things already), dont get the rack. All of those things are required to turn an unheated rack into a safe heated one.

If you have a heated room to the low to mid 80s and a ceiling fan, then you can use an unheated rack. The issue with heated rooms is there is no thermograde to allow the snakes to thermoregulate.