1500 watt space heater with 2 levels of power, 750 and 1500, adjustable knob thermostat and tip over shut off function

$18 when I picked mine up


just responding about the expensive space heater part.

A completely enclosed rack will be tricky, ventilation? means you have to keep a constant heat on to heat incoming air

The best way to do a self contained rack would be to have 2 heating "pads" one for the cool side and one for the warm side, and adjust those as needed to keep air temps constant.