Well, I'm back from Paris. An amazing trip. Here's my feedback on militaria dealers in Paris.
Le Poilu - great range, lots of uniforms and equipment, particularly lots of French WW2 and American WW2 items. Pricing is OK, neither cheap nor expensive. Definitely worth a visit.
Louvre Antiques - this large antiques centre consists of a lot of independent antique sellers in a fancy large building next to the Louvre. Don't bother going!!! All the directory signs list a number of militaria dealers. None of them are there any more. The centre is 70% empty, the shops sitting unleased, and the few that are still there all look like they are about to go out of business, even though they stock top-quality, incredibly expensive antiques.
Clignancourt Flea Markets -well worth a visit. Who knows what you will find? I discovered two dealers who specialise in militaria, both near Rue Paul Bert. Tend to be a bit pricey, but you might get lucky.
Port de Vanves Flea Market - you HAVE to check this out. It's on every Saturday and Sunday, although be warned the stalls start to pack up and leave from about 1pm on. Such an incredible variety of stuff on sale, and at really reasonable prices. It's like what Clignancourt used to be. I can't guarantee militaria, but you will be fascinated by all the old stuff on sale. I picked up three WW1 French medals, for 10 Euros each - ridiculously cheap.
Cheers,
Bungo