The Greeks might get even more money if buyers were able to claim independent sovereignty and set up a tax haven. Perhaps this could be a model for other highly indebted nations.
You buy the island, develop and Greek communists will seize it to “throw out the ‘neo-colonialists.”
Not to mention that Greece doesn’t have enough people to work on those islands. Immigrants are heading OUT of Greece and Greece is desperately trying to keep them (offered citizenship too to many)
Then commission up a social branding company to produce your sovereignty's flag, anthem, postage stamps and CIA factbook profile. With this, you can issue out passports, start a bank, a casino or several and apply for U.N. membership so you can have a vote and possibly sit on the Security Council.