The only one I have come across was a Randonneuring bike from the early 50's. I did a little research, the marquee did not last long but was endorsed by some rider back in the day. I don't know a real value but it started at $1200 and I last saw it listed around $850. But it was a complete bike in nice condition and very original. Racks, light, suicide shifter etc. It's one that got away, I regret not making some kind of offer but was hoping it might come down a little more.
It's a lesser known name and F/F only so I wouldn't pay too much incomplete like that, but I'm not a French bike guy and that is my only experience, so I would be pretty low in this case.