Some of you might remember this posting on clubsnap last year.
Found it on the internet a few weeks back and the fair was last weekend in a town called Bievres outside Paris. Takes about 45mins from PAris by RER (since you have to change train) or if you have a car its much quicker. The whole town centre turns into a flea market for 2 days in a year starting from noon Saturday and the whole of SUnday. The sellers are not all French. There were germans, british, italians and I think I saw KEH (big 2nd hand american shop specializing in second hand stuff) there too.
I'll post pictures soon.
Other than the antiques and hard to find stuff, nothing special about the current range of lenses. They're expensive for a used item. You could almost get it new in Asia for that price.
For those of you planning to come next year, keep an eye on this website... hopefully they will publish the date of the next outing...