Hi Richard,
Welcome back.
A good starting place is the Buyers Guide listed under “Model Guide” on the website.
You can also access past copies of the magazine and browsing the adverts should give you a good idea of what you can expect to pay. Past articles will also give you a good idea of what to look out for.
As regards what relative costs are in France, maybe Bob Street (ex editor of FP) could give some advice. He is now full time in France.
Where in France are you thinking of? Or have you not got that far yet?
Roger