Running through Paris the other day, we ran into Le Labo, the perfume store! Based in NYC to our knowledge, we were by the Mabillon metro and it was right there 6 Rue de Bourbon le Château. It has such a New York vibe to it, you really forget you're in Paris.
They had the interesting selection, including the murky 'Thé Noir 29' and really excellent 'Figue 15'; they have so many scents. It was great -- you could just browse the scented cards at your leisure, it was very casual.