If you have $8.6 million sitting around, you could buy your choice of any number of posh penthouses in Miami, or you could look a bit farther south and buy your own private island. An island dubbed East Sister Rock just off the coast of Marathon is on the market. It comes complete with a 5,000-square-foot home that's powered by wind and solar energy. 

The island has been on and off the market since 2011, when it was originally listed for $12 million, according to Curbed Miami. It was recently re-listed at the reduced price. (However, if you're interested, you can also rent the island for about $1,000 a night.)

The island is a three-minute boat ride from mainland Marathon (and about a two-hour trip from Miami). You can also travel there via helicopter thanks to the helipad on the premises. Though, that's probably not the most sustainable means of regular transport. 

The circular island is surrounded by a coral reef and is located near many choice fishing areas. 

The house, built in 1980, has three bedrooms, two bathrooms, and 2,500 square feet of veranda space, allowing 360-degree views of the ocean. The Bahama-style house sits 15 feet above sea level and features hardwood floors throughout. A guesthouse provides another bed and bath. 

It's basically the luxury ideal of off-the-grid living. 

• Real Estate