A deposit will be requested upon arrival, it will be between 200€ and 1000€ depending on the sites, per accommodation.
Preferably to be paid by bank check or possibly cash (a receipt will be provided) or by credit card. This deposit will be returned to you on the day of departure after the inventory or by mail within 8 days outside the opening hours.
Note that some residences can ask for a second deposit for the cleaning.
You will also have to pay the tourist tax. The amount of this tax varies depending on the station (between €0.50 and €3 per person per day).