A thermostat is the most important thing you can buy for your collection. Buy the best you can. When you buy cheap you get cheap. Also when you buy cheap it will usually cause you more in the long run.

The Herpstat 2 is a great choice. I have two Herpstat 1s, a 2, and a 4. They have all given me great service and have yet to let me down.

Watch here, Fauna, and Kingsnake....maybe even Craigslist for them. They pop up from time to time and you can get a good deal on a slightly used one. I have bought a couple of mine used from people that got a different one or got out of the hobby.