Here are some inexpensive models (wow - cannot believe how cheap they've become). You would need one that operates off of 120vac and controls the 120vac line going to the pot. Very simple to use. Hook up the thermocouple to monitor temp. 120vac to run the PID controller and 120vac (separate line) to the PID and on to the pot to control the power. I don't know if these below are any good, as I've always used industrial quality (don't want your $$million process to go down due to a $50 controller). The thermocouple will likely cost as much as the controller.
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