Siesta Key, FL Sheds, Carports, Garages and accessory dwelling Units for Sale Sheds for sale in Siesta Key, FL have an average price of $3150.00 with an average square footage of 88. The average cost per square foot is $35.80. ShedHub.com is aware of 2 dealers within 20 miles of Siesta Key FL. The most popular shed styles at these locations are High Barns, Mini Barns, and Garages.