Calais to Les Arcs and back will cost you 3 tanks of diesel, tolls are approx €75 each way. I do this trip 3-4 times a year in various diesel cars, fill up in Calais, refuel again in Albertville on the way there and on the way back, fill up again in Calais, all at supermarket prices.
http://www.prix-carburants.gouv.fr/