Required reading

Price Theory: An Intermediate Text This is a book written by David Friedman, the son of the late Milton Friedman. David lived with a top-notch economist and economics teacher. He also got a degree in college -- in physics. I'm sure this enhanced the clarity of his explanations. In any event, this is a wonderfully clear book, and although there's some content that's missing from the webbed version (due to copyright issues), and the webbed version isn't as nice as the printed version, it's free. (Though he does have a section titled, "Why you should buy this book".)