When my wife and I were in Paris a few years ago, we spent a lot of time poking around in several of Paris' many flea markets. There is something for everyone and there is usually one open every day of the week. We particularly liked the one in Porte de Clignancourt (many covered stalls) and Porte de Vanves (all outside). We also liked the book stalls along the Seine. Hope this helps.

Sam in Crescent City