you will have to pay at least 300-350EUR for a one room flat in France. Good apartments will cost much more than 400EUR and please note that Paris or Nice are more expensive than any other property in france a good alternative to a small apartment with one bedroom is sharing a flat with others. you'll have your own room but share bathroom and kitchen. you'll get more (nicer location, view, ...) for money. especially university students share their flats, so it is perfect if you are young and/or if you are searching for a cheap solution