For buying films:
http://www.selsdargent.com/ (hoping that Damien Féau is in a good mood!);
For having the films processed:
http://stephane-cormier.fr/fr/index.php (Stéph is always in a good mood!).
both guys are located at the same address, 7 rue Taylor Paris 10° (Metro station: République or Strasbourg-Saint-Denis)
You can also have a look at the books and prints sold by Argentic (http://www.argentic.fr/)