At any point in history, has an individual ever purchased an entire country - using their private wealth?
Specifically, I'm looking for any examples of somebody who has purchased an entire already-existing country - not simply buying significant amounts of land, and then founding a new country from it.
Ideally, the person who purchased the country, would then be in charge of its governance. However if no such situation exists, examples of things that come close would be welcome too (such as owning all land and infrastructure - but not directly governing the country).
Has such an event ever happened in history?