Apart from hotels, hostels and couch surfing there is also the option of Airbnb or else air bed and breakfast.
You can find very good deals of Airbnb rentals along the French Riviera especially when its low season. With Airbnb you can choose between staying with the owner of the house/apartment or renting entirely for yourself.
The prices differ based on the period you choose to rent, the area of your choice and of course the type of the accommodation. Airbnb is usually cheaper than hotels so if you are worried about your budget Visit The French Riviera has made a list for you to choose between the most affordable apartments.
Whether you are interested in long term or short term renting there is always an option for everyone.