I know Leboncoin well! I found my 979 on there for 120 Euros, as a complete bike. I've found a few other bargains on there: a complete and original 531 Mercier for 70 Euros, a complete, original (down to the tyres...) Dawes Galaxy for 45 Euros, a complete Mavic groupset from a guy near Narbonne, a Gilco-tubed CBT Italia for 50 Euros and I've just found a '91 Scott mountain bike for 60 Euros from a bloke in Nimes. Like you say, the retro scene here isn't really that big and people don't appreciate what they have.
When I think I came here for the weather and the wine...! :shock: