It is my unlearned opinion that it is not correct to say that Ranco or Johnson thermostats are not as reliable as a Herpstat or Helix. A proportional thermostat should hold temps rock steady while a Johnson or Ranco will let temperatures fluctuate a couple of degrees which is no problem at all. They are quite reliable. A young man has for sale on this site a used Ranco wired up by Reptile Basics for $55 shipped. Any of these would be a better choice than Zoo Med, but even that will do for a while if that is all you have.