I'd be surprised at that. The material cost hasnt dropped 40% since 2006. My dads friend is a builder. The cost of building a house has remained pretty steady in MN at about 115-125\sq foot.
But what he and many other builders are doing is buying homes on auction because they cant build them that cheap.
Yeh, but I'll bet that the price of subcontracted labor for many parts of the process aren't nearly as low as in Arizona, where many construction sites don't have anybody on hand who's a native english speaker... Which doesn't stop Arizonians from scapegoating illegals in the slightest. They're great when you're making money off of 'em, however...