Hello and welcome to Flyertalk!
Some more ideas:
- purchase discount CDG-xxx-ATH roundtrip on some Star Alliance carrier and discard the return leg. This will be much cheaper than buying one-way tickets on legacy carriers. However, this will not allow a stopover longer than 24 hours in the transit country, should you wish to visit it.
- a
Star Alliance European Airpass , assuming you are flying with them to Europe. 3 segments minimum, but stopovers become possible.
- buying some form of rail pass, paying attention to the countries covered (for instance, the common
Eurailpass doesn't cover the former Yugoslavia, which would however be quite an interesting train trip).
- get to Germany, and buy a one way air ticket on one of the discount German low cost
carriers flying to Athens . For instance:
-
Air Berlin from Berlin, Hannover, Köln, Münster, Nuremberg, etc. ~€140
Having done the train+boat trip through Italy to Patras (the ferries I am aware of do not go to Athens, but to Patras, where you'll have to take a bus or train to Athens) in my youth, I cannot overly recommend it, unless visiting Italy is the major purpose. Very tiring, all but seamless, and quite the opposite of civilized travel IMHO.