In reply to minty1984:
There's "Horizon Millau" as well, but I've never seen it open (admittedly I'm not in Millau that often).
There's a decathlon in Carcassonne, but it's not the biggest city so you might be out of luck...
Try
http://www.acheter-ou.fr/ and write "materiel d'escalade" in the first text box, and then the city in the second.
Post edited at 18:40