The value of all land for sale in Saint Johns County recently was approximately $638 million, representing a combined 913 acres of land for sale in Saint Johns County. Saint Johns County ranks 30th in the Orange State for the total number of acres of land currently advertised for sale. Of all land and rural real estate for sale in Saint Johns County, Saint Augustine had the most land for sale. Saint Johns County is Florida's 36th biggest county (821 square miles). It's located in the Northeast Florida region of the state.