hmm,
tricky one. a few tips, but unless you have a reduction car for either/both countries you are looking at paying a hefty sum.
Vueling.com fly from zurich to paris, usually much cheaper then full price train tickets
easyjet fly geneva paris, not really sure about prices
or try Covoiturage.fr
this car sharing website is pretty good within France but not so good for international journeys. so if you are going to use this I would recommend trying to get to the nearest big(ish) French town by train or bus and then get the lift from there.
otherwise I wrote an article about cheap train tickets here (supersaver)
http://zurichexpats.com/cheap-train-...s-switzerland/
I think these tickets are only available until the end of February, and not for major international journeys. but it might be able to get you over the border to a lift cheap enough? or to the flight in Zurich.
Otherwise i'd recommend getting the discount cards if you are going regularly as they usually pay for them selves in the first ticket or 2