At this time last year, lowballers were combing the Hamptons for underpriced property like old men with metal detectors. Now out in Bridgehampton, somebody with loads of money has broken a real-estate record by renting an eleven-and-a-half-acre estate known as “the Sandcastle” for $500,000. For two weeks. In July! That beats Howard Stern’s million-dollar rental (for the entire season) on Meadow Lane back in go-go 2007. This mansion, built and owned by luxury developer Joe Farrell, has nine bedrooms and eleven-and-a-half bathrooms with tennis, squash, and racquetball courts, a bowling alley, and a half-pipe for skateboarders. It’s also on the market for $49.5 million. Who has that much richness to rent a property for just two weeks? A publicist from the Corcoran Group, which handled the sale, wouldn’t comment on the tenant or any other specifics. Let the speculation begin.