What would buying even mean in this sense? Even countries don't "own" their ccTLDs, but ICANN has made considerable efforts to outline policies that go "we really need to treat ccTLDs like the countries own them to avoid tensions over internet namespaces". That's why most gTLD rules don't apply to ccTLDs.

Countries "own" their ccTLD in the sense that they (or most) have the military prowess to defend their usage of their ccTLD if ICANN, or the servers at root-servers.net, were to stop resolving TLDs appropriately.