An interesting phenomena I have seen lately is that there is very little premium for sq footage above 2800 sq ft. People dont want to spend the extra money for all that uneccessary space. Homes are going for about $300/sq ft up to about 2600 sq ft. Over that the extra sq footage is going for $100 or less. In some cases (i.e. above 3500 sq ft) it has almost no value.

As a buyer its a relative bargain if you want a house that big. As a seller its become a bit of a sunk cost.