I found these items that would work for my setup for $60 shipped, not including a box, so I'm estimating all in would be ~$100 for a 25A RIMS heating controller. My element is rated 2kW at 120V so the current would be 16.7A.
However, for now I think I'll just be the temperature controller myself, man in the loop, by watching the mash temperature and adjusting my propane burner.
90-265V Digital F/C PID Temperature Controller Thermostat TA4-SNR SSR output
D PT100 Temp Sensors 1.5"L,1/2”NPT with Telfon Cable & Detachable Connector
25A AC Solid State Relay SSR with Heatsink