I get a newsletter from SCNF and this was just brought to my attention: http://special-offers.en.voyages-sncf.com/en/ouigo-low-cost-train. It might help someone with cheaper fares Paris to the south of France. Be sure to read the fine print because some restrictions do apply, including ones for luggage. What caught my eye is that you can get tickets for travel between 6 July and 9 December. They just opened up today.
Here are some of the details from that fine print:
OUIGO rate from, per person, per trip, one way with OUIGO and are valid as long as stocks last. Available from 5 March 2014, for travel between 6 July and 09 December 2014. Ticket exchangeable up to 4 hours before departure and only against another OUIGO ticket, a fee of € 10 when done via the Internet and a fee of €20 when done through the OUIGO customer plus any difference between the ticket prices. Ticket is not refundable. Luggage included in the ticket price: a hand and a cabin baggage. Online payment. Self-print ticket required. Offer not valid in conjunction with any other SNCF offer or discount rate.