A new Mooring buoy found under Vehicles / Boats, costs 0. You need Paradise Island ( or a later pack ) for the buoy to show in your game.
1. Board Boat
2. Boat Here
PS. I was sitting yesterday by the sea side and was watching all the recreation boats anchored to red buoys so this is how the idea came about. Also, EA makes the most boring objects. A wooden post !! Where would you find these, in the jungle ??