16 Binney Lane, Old Greenwich, sold for $3.450 million. This was pretty much a brand new house created from a 1961, out of the flood zone (of course down there, you might want to keep a dingy available should you desire to leave your house during floods) and all in all, decent living. And Binney’s a great street.
The builders/sellers paid $2.250 million in 2012 and as noted, rebuilt and expanded it. I don’t see the huge profit here (they had to reduce it from $3.750, so perhaps that’s why) but I suppose it’s like food stores: high volume lets you accept low margins.