When you buy a property in France this always has to be done through a Notaire. The Notaire charges the buyer a fee and collects taxes on the purchase price. In addition the Notaire will make an extra charge for other services, if necessary, such as for registering a mortgage.
I have put a calculator online at Notaire Charges which gives an accurate idea of the charges, taxes and fees collected by the Notaire  for a property in France.