Saint Helena:

Saint Helena produces what is said to be the most expensive coffee in the world. It also produces and exports Tungi Spirit, made from the fruit of the prickly or cactus pears, Opuntia ficus-indica ("Tungi" is the local St Helenian name for the plant). Ascension Island, Tristan da Cunha and Saint Helena all issue their own postage stamps which provide a significant income.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What does Saint Helena have the most expensive of?
coffee