You can buy a 6500w+ electric start generator and have a 10 circuit transfer switch installed for 1/4 of that, quite possibly less.
Mine won't run my WHOLE house as the range, air conditioner and water heater are electric...but it'll run most everything else save a couple outlet circuits.
I brought up that option to her, too. "A smaller generator won't cost as much".
But ~$4k for a 20Kw Generac really is a pretty good price. We will soon have a gas range, but the water is electric. As is the obvious AC. Not sure how small we could go that'd still run the blower for the heat, though. Do have gas heat.
Perhaps a smaller generator + a ventless gas insert for the fireplace (vented gas log now) would be a rather economical way to go.