The French Government Tourist Office has a full list of tour operators who run all types of tours, including camping and special interest holidays. There are hundreds of these in France, offering very simple accommodation at very low prices. There are hostels in all major towns. Stays are usually limited to three or four nights or a week in Paris. Hostels are open to all members of the National Youth Hostel Association upon presentation of a membership card.
Lists are available from national youth hostel organisations.