As Gale said the Accurite digital thermo/hydro is probably the best bet for measuring temps and humidity.
A IR temp gun is also highly recommended for measuring your hot spot surface temps.
We use Herpstat for our main racks and incubator and absolutely love them!
The other one Gale is referring to is the Hydrofarm. It is a decent on/off thermostat for the price. We are currently using one for our QT rack and our Leopard Geckos.
Here is the link for the Hydrofarm
And the link to SpyderRobotics