Du hast Recht, das muss man alles selbst zahlen.
Auf der Webseite steht es klar und deutlich:
The basic Admission ticket gives visitors access to the Gardens & Grounds of the plantation. Please allow a minimum of 45 minutes for the self-guided walk through the main gardens. However, please allot additional time if you plan to visit the Swamp Garden, Barbados Tropical Greenhouse, the Petting Zoo, the Antebellum Cabin, the Orientation Theater, the Horticultural Maze, and the Wildlife Observation Tower. This ticket is valid for another visit for 6 days after purchase date. This basic admission ticket does not include the House tour, the Nature Train, the Nature Boat, and the Audubon Swamp Garden.
@Palo: Mir wäre das für den Preis ehrlich gesagt auch zu viel.