I think the minimum price for setting up a TLD is tens of thousands of dollars, and it doesn't have to be a country it can be any kind of string, like .pepsi or .beef or anything.
New gTLDs (like .app) which receive multiple applications and have no clear owner are opened to an auction among the qualified applicants. Other more specific applications are given to the most qualified applicant (for example, i know the applicant for .ski has been endorsed by the USSA and FIS, the american and international governing bodies for skiing)
Almost $200k, actually, and that's just the fee to present the request; you'll still have to have the infrastructure to actually run the root DNS servers for your TLD(s).