not so much bellydance-specific stores, but a few places where you can get some good belly-related things...
-marche aux puces at the porte de clignancourt metro is good for jewelery, tribal belts and harem pants
-there's a store on boulevard de rochechaurt called 'espace orient' (i believe) and i think it's in between the pigalle and anvers metro stops, on the left if you're going towards anvers...you can find some good pieces there, all kinds of middle eastern clothes, shoes and jewelery...i bought my cane there
-the entire neighborhood around the la chapelle metro is good for indian clothing -really beautiful saris, nice accesories too

there are metal jewelery stores all over that sell some kuchi-ish things...one i know of for sure is on rue lepic, on the right side when you're coming up from metro blanche...

oh yes, also, there's a store that sells some jewerly and other indian clothing items at the denfert rocheraut metro..get out at the avenue du general leclerc cote de nos impairs exit...you'll see mcdonalds immediately when you get out, go north and it will be on the left a few stores down...

apparently there's a shop that sells real kuchi somewhere around notre dame but i'm not sure where exactly...
there's also one shop at the back of marche aux puces past the overpass that sells real kuchi

have fun in our beautiful city!

-erin