I just spent two weeks in Paris and Lyon and would *strongly* suggest that you bring all the film you are going to shoot on the trip with you. Everything over there was 25-100% more than Freestyle prices.
While it is expensive compared to US gear prices, be sure to check out Boulevard Beaumarchais just off (north) from Bastille. There are a number of specialised shops and then some general new (and general used) shops. One shop in particular had a lot of interesting/top quality old gear, Canon 7 with 50/.95, Leicas, Rolleis, etc. There's also ones specific to large/medium format. The street market near Place de la Bastille was very good for food, as well.
Also, if you're looking to do some bargain hunting, the large flea market up on the north end of town did not seem to be the place to find it, but you may have better luck than I did. Everything that I saw was way overpriced compared to what I see around the US, even on eBay.
I brought 40 rolls of 120/220, didn't burn through it all but it was close at the end, especially the day in the Alps watching the tour. My girlfriend brought her Spotmatic and ran through 4, I think. My brother borrowed an XA from me and shot 3 through that plus another through his LOMO fisheye.
Anyway, if I can be of any further help, I'd be happy to help as I can.