At Cieloverde Camping Village in Marina di Grosseto (Grosseto) camping costs as little as €18,- per night during low season with CampingCard ACSI. At one of the 1260 touring pitches you will get a discounted rate during the period . At this campsite you can not only use your CampingCard ACSI for inexpensive camping, you can also use your ACSI Club ID (as an alternative ID).
Very nicely appointed campsite in park with e.g. many play options for children. The site is 1km from the beach, but a campsite train will get you there, from where there is a walking/cycle path to the sea. Large, first-rate toilet blocks.