It depends

If you live in a house that has a fireplace, you need to cut two holes--one to blowout the cooking steam, another intake or makeup air. If the house is already finished, it is harder, but still can be done.
That is why I said she was looking at cheaper houses.
Most people buying a house look at the "surface" - the tiles, the hardwood floors, the sizes of the rooms, etc. A lot of the important stuff of a high quality house is inside the walls.