I had a whole house generator installed when i lived in Michigan. It ran about 7000.00, ran on natural gas. It requires upkeep every year. (tuneup, oil change, filter).
and ebout every 4-5 years a new battery. Having it done is about 200.00 per year. In mich. i was concerned about freezing in the winter. Here in the villages,
that is no concern. If you want it to run your AC, it will cost about 10,000.00.
A portable requires to much gas, or bottles of propane. If you add the cost of a underground tank, i believe the cost is to high. I have a extra freezer, and if i threw away everything i am out only around 500.00 or so. I just keep battery lights, candles, and a portable stove with fuel. and of course my bbq, with extra tank of fuel.