Actually it is pretty complicated. Casino distribution Group es selling them. Quite difficult to find the online store. You can try monoprix though I do not know whether it works outside France:

http://courses.monoprix.fr/magasin-e...50035,,1,.html

Hope it helps.

EDIT: Ms Moien bought one brand at the supermarket that sells doses for Nespresso coffee machines. I must devote a lot of time to think about some coffee that tastes as bad as that. It is a French brand La Maison de Café (Douwe Egberts). If you see it just run away ... and don't look back.