Another option, not mentioned until now is covoiturage or ride-sharing. It's becoming quite popular in France. The main operator in this space is https://www.blablacar.fr/ (I am a user/member but otherwise unconnected to them).

Beginning this year, rules regarding long-distance busses have changed so it's possible that cheaper bus-based options will appear very soon.

Another option, not mentioned until now is covoiturage or ride-sharing. It's becoming quite popular in France. The main operator in this space is https://www.blablacar.fr/ (I am a user/member but otherwise unconnected to them).

Beginning this year, rules regarding long-distance buses have changed so it's possible that cheaper bus-based options will appear very soon.