I got several Temp controllers from Ebay, Same with the (SSR's)Solid State Relays. All my High-Temp Wiring came from the Electric Range I salvaged to make it.
I got the range for free!! I called a Local appliance dealer (Maytag) and asked for an old broken unit. Didnt care what color ar shape.
They haul off the old units when they deliver the new ones, sometimes they store the old ones for parts.
They set a nice looking unit ( ugly Gold color) out their back door, I told them I was probably going to blow it up.
They wanted pictures,,,,,,
Anyhow, good raw material! Sheet metal, burners, lot's of wiring, you could even use the ovens thermostat and sensor for ANY Unit, just add a SSR
Got a Gas Grill? Use an Gas Stoves Temperature Control. (Not the orifice and burner, just sensor and solonoid installed in-line with your grills fuel supply)