[Selanne_200]

The foundation costs would actually be more because you would have to dig deeper "the height of the basement floor", more lumber and joists because of the additional floor, and also your foundation form would be different. I say if you go for a basement if you have the money or can afford it, because you won't regret it;however, I wouldn't say it's marginal. With the cost of finishing and everything, I would say factor in at least another 80,000-100,000 at least depending on the size of your basement and whether you'll need special foundation footing in the area you're planning to build.