You need good thermometers and a thermostat, stay away from pet stores, as all they sell is overpriced junk.

Get this thermometer/hygrometer from Walmart, it costs $12 and measures 2 temperatures and humidity (the probe goes on the hot side directly above the UTH on the cage floor, and the unit goes on the cool side)



You will also need a thermostat to regulate your UTH, a thermostat is the most important part of keeping reptiles:

Here are 3 good thermostats, as I said before stay away from the junk sold in pet stores

Budget: http://www.amazon.com/Hydrofarm-MTPR.../dp/B000NZZG3S

Mid-Range: http://www.reptilebasics.com/ranco-etc-111000-pre-wired

High Quality: http://spyderrobotics.com/home/products.html