If you're looking for a temp controller to make a proofing box, here's one that works on 120/240 volts, heats and cools, and is about $50 delivered. Looks pretty slick!
ETC-111000 Ranco Digital Temp Control 120/208/240V
The GOLDLINE SP-30 ALTERNATIVE
The Ranco ETC is a microprocessor based electronic temperature controller designed to provide on/off control of heating and cooling.
The ETC is equiped with a Liquid Crystal Display(LCD) that provides a constant readout of the sensed temperature, and a touch keypad that allows the user to easily and accurately select the set point temperature, differential set point, and heating or cooling mode of operation.
The unit can be operated on either line voltage, 120/208/240VAC. With its wide temperature setpoint range and selectable heating or cooling modes, the ETC can be used for a wide variety of applications such as Research, Science, Laboratory, Education, Aquariums, Hydroponics, Pools and more.
Some of ETCS Microprocessor outstanding features include :
Large and easy to read LCD
2 Inch Long x 1/4 Inch Diameter
8 Feet of Cable included
Remote Sensor can run up to 400ft away
SPDT Output Relay
Wide Range: -30 to 220°:F
User selectable Fahrenheit/Celsius scales
Lockout Switch to prevent tampering by unauthorized personnel
Simple 4-step keypad programming.