Communication in English is a little strained but he's a good guy and supplied the seat covers I had made in a bespoke fashion. He is also the shop on eBay and less expensive the der Franzose.
Joe
You don't say which make or model of carburettor your R4 has, but eBay France and www.leboncoin.fr are good starting points. Try entering 'Carburateur R4 4L Renault 4' and see what comes up. Prices seem to be going up!
Is your carb actually beyond repair? If not, and it's a Zenith, have a look at the various threads on the forum - you might be able to get a repair kit and fix it yourself.