Minnesota + four-cylinder engine = disaster.?

I recently bought a 1999 Subaru Forester which only has the boxer 4-cyl. in it. it's a great car, but I live in Minnesota where it can reach temperatures of -20 or colder. I don't have a garage space and I'm worried it won't start without an engine block heater. is there a place where I can have one installed? No I am not moving and NO, I am not buying another car.