Let us breathe the air of the Enchanted Island. There are no islands any more. My search seems to indicate that, basically, deserted islands are about the only hope left for those who just want to be left alone. Yet even then you won't be left alone. Nevertheless buying an island won't buy you freedom.
Sovereignty is something nations are willing sell only to other nations.
Though just barely. But don't give up just yet. I should have said to be located, because so far Oceania consists of little more than architectural drawings and hopeful dreams. You see, it turns out that artificial island building is expensive. Like, one billion dollars expensive.