Hi, yes I live in France, have done since 04. But I have three right hand drive Volvo's all of which are re-registered onto French plates & log book etc.
2'nd hand cars here are very expensive.
In 09' I bought an 850 in Derby for 850 quid, a 96' model. Same model here then was circa 2500 euros.
In Nov' I bought a 2004 V70SE Auto for 1500 quid, same here 7-9000 euros.
Yes a private sale here may save some on those, but even then you'd be lucky to get say, an 850 for less than a grand and with less than 300kms too.
Some sites to search on for you:
http://www.leboncoin.fr/
Thats a general for sale of all sorts site. Very popular and some nice cars do pop up.
http://www.vfl-fr.com/forum/
http://forum.univers-volvo.com/
Those two are Volvo forums with 'for sale' pages.
I prefer univers myself, but use both regularly.
Hope this is of use & if can help further don't hesitate to ask.
Good luck