I would suggest, if at all possible, going with a herpstat thermostat. If you look around, that is what everyone recommends and they seem to do so for good reason. That is what I'm going to be purchasing. They are pricey, but they are a good product. That will be around $100-$125.
Thermostat and thermometer/hygrometer are two (three actually) separate things.
Thermostat - controls and tells your heat source when to turn on. You actually plug your heat source (UTH) in to this device and when the thermometer probe attached to this device gets to your set temperature, it will turn the heater on.
Thermometer/Hygrometer - this just measures temperature and humidity... This is mainly just to show you what the room (ambient) temperature inside the cage is, and what the humidity inside the cage is. You can find them at Walmart, Lowes, Home Depot, etc... something like this will work just fine:
http://www.walmart.com/ip/INSTEN-Whi...Meter/42555963 I have two of them in my cage, one on the warm side, and one on the cool side, as I like to know the temps all the time, on both sides. They will run you $5-$10 each, but are well worth it.