generators are not that expensive..you can buy a small one at Harborfreight likel for under $100...
I would imagine the guy was talking mainly about permanently mounted and sheltered home stand-by back-up power systems, often diesel or NG, but who knows. "None of his business" applies in either case.
Those $100 generators are good for 800 watts. Not much good for anything but lights. Expect to spend around $300 for something useful.