"It is no crime to be ignorant of economics, which is, after all, a specialized discipline and one that most people consider to be a 'dismal science.' But it is totally irresponsible to have a loud and vociferous opinion on economic subjects while remaining in this state of ignorance."
The print version of Murray Rothbard’s The Betrayal of the American Right is gorgeous and well worth the price, but Mises.org has made the entire book available for free online in PDF and HTML: