Potentially nothing, but apartment buildings don't move, so an artillery shell at one-hundredth the cost would probably be the preferred option anyway for nations motivated toward such things.
Well, I've seen our allies use a $249,000-a-pop FGM-148 Javelin anti-tank missile against a solitary soldier where a $0.49 rifle shell would do [1], so I don't price matters. Especially when we're giving the stuff away.
