That kind of depends on how you price freedom of expression and assembly. Of course, you could argue that Occupy LA didn't need to freely express itself and assemble for quite so long on the lawn surrounding City Hall. According to the Los Angeles Times' L.A. Now blog, the cost of cleanup could hit $1 million.
That's in the context of a city budget deficit that's projected to hit $200 million for the fiscal year.
So let's say it does cost $1 million to make City Hall look fresh and new again. That won't seem like much when the cost of cleaning up after the recent wind storm is taken into account. Pasadena and LA together could wind up spending $5-6 billion to take care of that mess.
Still, Occupy is going to need to be mindful of these costs moving forward. America's large cities are facing post-financial crisis budget struggles. The movement probably understands that there are costs that people are willing to tolerate, associated with the exercise of rights. But people also have limits, when costs rise too high.