Hi Lemonkid-
An interesting one to look for in Paris is Aux Vieux Campeur. They have stores throughout the Latin Quarter. Otherwise any of the major department stores (BHV, Bon Marche, Fnac, Galeries Lafayette, Printemps, Samaritaine) will have an outdoor adventure section and that might be easier if you just need a few items.
And you can buy compeed at the pharmacie in Paris as well.
Best,
lynne