Actually, that's the wrong question, since the law-enforcement lobby would make it very, very expensive to abolish the police through legal channels, and any violent attempt to bypass legal channels would probably end up having the opposite effect.

What I mean is this: if we pushed the Rothbardian button* and made all the cops go away tomorrow, how much would it cost to implement a private libertarian replacement, where person and property are protected, and victimless so-called crimes are nobody's business but the nonexistent victims?

Gil Guillory, et al. have crunched the numbers. He summarizes on LRC. Here's my summary of his summary (dollar amounts are per annum per household):

* Murray Rothbard, For a New Liberty, final chapter, "A Strategy for Liberty":

"The libertarian, then, should be a person who would push the button, if it existed, for the instantaneous abolition of all invasions of liberty."

** If the payouts were capped at your homeowner's insurance deductible, it would only be $25.