If you want to visit one of the Greek Islands, all you need to do is book the right flight to Athens, and then use Google Flights to search for Roundtrip tickets from Athens to Santorini or Mykonos. These roundtrip flights could be found for as low as $50 on Budget Airlines like Ryanair. Just remember that budget airlines charge extra for everything (luggage, carry-on, choosing your seat).
Airport Code: ATH
Airline: Air Canada / Swiss
Availability: September 2017 – May 2018
Nearby Airports? No
Sample Stops: 1 (Montreal/Zurich)
Search Here (Momondo)
Sample Pricing