I use a Lasko Low Profile Room Heater, which has a built in thermostat. It has been great for the past, at least 6-7 years. I also have a back up one which is the same exact model except digital, new in the box, to use once this one goes out.
I use this, alongside with our natural TX weather. For late spring and all summer, the heater is not on hardly ever, as my snake room stays at a nice 76-79 with the AC vent closed. Fall and winter, and this heater is on.
I saw new models of this type at Home Depot the other day for $40. For me, they have worked great.