Generally, tropical islands fetch more than those in temperate climates, as do islands with quick access to civilization. Another factor: the stability of the local government. An islet off the coast of Nicaragua is currently selling for $144,000 an acre, while a 45-acre beauty in the British Virgin Islands is listed at more than $1 million.
Although generally speaking this is a pretty accurate summary. However when purchasing a private island their are and endless number of criteria that one should look at. In addition to climate and local government one should also look at development opportunities and laws, size of the island, access to resources such as fresh water, access to the mainland, whether the property is freehold or lease hold, commute time to island and of course investment potential. The importance of any one of these factors varies from person to person which is why it is important to have a private island expert available to assist you in the purchase process.
For more information on owning, selling and renting a private island visit the resources section at private islands online.