Some other options:
Propane:
-
Camp Chef burner - can be found for a bit under $100 and has useful legs to bring it to a height where you can run the wort off straight into the fermentor.
Electric:
- Various 3500W induction hot plates - need 230V supply and induction compatible pot.
- Various 1800W induction hot plates - need an induction compatible pot, and probably some insulation of the pot.
- Water heater type immersion elements, either installed directly into the pot, or on a removeable "heat stick" - up to 2kW on 120V, up to 5.5kW on 240V*.
- Blichmann Boil Coil - installed in the pot, up to 2.4kW on 120V, up to 5.5kW on 240V
- All in one electric brewing systems from Braumeister, Grainfather, etc. etc.
Both of the latter need some kind of control panel, and GFCI breakers/outlets installed. See the Electric Brewing subforum for details on all the electric options.
*all electric elements are specified at 120V/240V. They run at reduced power on 110V/220V.