I was buying tickets from Brusells to Limoges and have stumbled upon this useful trick that gives you much cheaper tickets in some cases. First, don’t buy from thalys.com, they are the most expensive.
Second, when you buy from www.voyages-sncf.com, buy each segment separately. For example when I was buying tickets from Brussels to Limoges, when I typed that in the search form I got the final price around 200 EUR. When I booked 2 tickets, one from Brussels-Paris and then Paris-Limoges, the total price was 100 EUR. That’s a 50% saving!
This seems to work for other tickets as well on SNCF. For some reason you don’t get the cheapest rates if you allow the system to make the connections for you. Hope this is helpful for someone.