Here are some good thermostats:
Budget: http://www.amazon.com/Hydrofarm-MTPR.../dp/B000NZZG3S
Mid-Range: http://www.reptilebasics.com/ranco-etc-111000-pre-wired
Best: http://spyderrobotics.com/home/products.html
Get the best thermostat you can afford. There is a massive difference on quality/safety in-between each of the 3 thermostats I listed above.