What is Luxury Real Estate?

We read the headlines that the "luxury" real estate market is doing well but what does luxury mean?  One person's idea of luxury isn't another's.

Luxury in the hottest & most expensive real estate markets is quite different from other markets.  Sotheby's, in a recent article on the luxury market uses the $4million mark but I would push it higher.  Why higher?  Too many homes on the West Side hit $4million, even for just lot value.  Of course it depends on lot size & type of home too.  A $4million home on a 33ft lot might be quite nice but on a 40 ft lot, could just be lot value.

Maybe the criteria should be a number that a reader would instantly know represents a certain type of home.  Maybe that "luxury" number should be more like $7-8million.