oh, i am not asking you to research this for me. i just thought there might be someone around here that already knows these things and could just share...which would mean 2 minutes from their life
i found out that the best way is to book a flight with Swiss 2 months in advance and it would be 300chf per return flight...
the train through TGV is 170 eur return ticket...so maybe someone knows how much it is if we buy it through sbb and what offers do they have for a "in advance" booking...