Typically the building of housing and the use of land in fairly exclusive resort/beach/etc. communities is very tightly controlled. People in the Hamptons on the weekends don't want it to be another Manhattan. They already probably have a condo in Manhattan. Some real estate is desirable because of location (often beach/mountains) and community exclusivity--and often some degree of accessibility to wealthy population centers. (As you go up the Maine coast waterfront property is not necessarily outrageously expensive.)