WITH the wind riffling the marsh grasses, Russell Groves borrowed an aluminum ladder from the construction crew working next door and climbed up on the roof of the tiny white house to survey the icy bay beyond.

The house is for sale for only $299,000, a rare case in which someone in search of a modestly priced house on the South Fork of Long Island can buy a lot extending into the marshland without anything — or anybody — blocking the view.