To Saddy Delgado, the listing of the vacant lot in Coral Gables’ tony Gables Estates is remarkable for a few reasons. It’s big – with 2.55 acres and 515 feet of waterfront. It’s exclusive – at 20 Casuarina Concourse, the site of security firm founder George Wackenhut’s onetime replica of a medieval estate, Delgado said. So the asking price of $13.5 million should raise no eyebrows. Except the parcel exemplifies the demand for waterfront property in South Florida – and what people are willing to pay, said Delgado, listing agent and a top-producing broker associate with Avatar Real Estate Services. A version of this article appeared May 10, 2013, and can be found here.