As Jeff Bezos says, your margin is my opportunity. So yes, it would drive costs down. But we aren’t even there yet because the houses aren’t being sold because they’re too expensive.
Another way to pad your profit margins would be to raise the asking price of the $360k home by $100k. There is a reason people aren’t doing that.
Amazon deals in commodity goods that are easily substituteable.
Housing is different because every single one is unique (by virtue of location) and also incredibly scarce (again, location).
Housing markets tend to strongly fight any tendency towards underpricing. When a house is underpriced, buyers will get into a bidding war and push the price back into the fair market price.
Another way to pad your profit margins would be to raise the asking price of the $360k home by $100k. There is a reason people aren’t doing that.