How much money are all these occupy movements costing municipalities?

You here on the news so-in-so city spent X amount of money clearing an occupy camp, just to have them return, or set up at another area to do it all again. It seems to be like an ongoing tab, but how much is it costing cities nation wide? What good is spending the money if you are only doing it temporary and not so the money won’t have to be spent again for the same reason?