Hello, I'm from Paris and I can now say that you won't find this kind of records in Clignancourt (as dave did) only if you're really really lucky, as it radicaly changed!...there's only hip hop clothes shops, or antique dealers in Clignancourt now.
I used to find great stuff in this market in the end of 80's & 90's (US 45's, acetates, EP's) but now it's finish...it's better to try the secondhand fleamarkets around Paris (or record fairs)
Romain