A-Life thermostats - say what you will, these are awfully good units. We sell more than 100 a year and I've heard of 2 failures in 6 years. I personally use them on my quarantine and hatchling racks. MUCH safer than running racks wide open with no thermostat. For your more expensive collections or breeding animals, we recommend stepping up to the Herpstat units though.
$35

 

We are SO excited to finally be a Spyder Robotics distributor!!! This is the original Herpstat, quickly becoming THE standard in the reptile world. I would definitely use one of these on any incubator and on your high dollar herps. Accurate to .1 degree and has an incredible track record. Night drop cord available for $25.
$109

This is the Herpstat II. It controls two zones in one unit. It has night drop built-in as well. You can manage heat sources with one unit while saving money!
$219

This is what we prefer for our setup. It's a single unit that controls FOUR zones! Incredibly convenient for the larger collections. It also has built-in night drop.
$319