I agree with the advice so far given to you...remember before all the electronic gadgets, incubators were thermostatically controlled by the wafer system, billions& billions of eggs have been hatched with this inexpensive system and I'll bet billions more yet to be hatched....Modernization has brought todays consumer into the "set and forget" system and magically a chick appears. Controlling temp, humidity and turning of the eggs.....simple
I hate the idea of putting $150 out for a stryofoam box and believe a home-made cabinet is the way to go.
Good Luck, HappyHatch'en