An OK one is "Economics in One Lesson" by Henry Hazlitt, although it dribbles off some after the first few chapters. "Free to Choose" by Milton Friedman explains the market pretty well, while "Economists on Trial" by Mark Skousen is also pretty good. Try Milton's son David. He is far more lively and articulate than his father(and often riotously funny). Hidden Order and the Machinery of Freedom are both good reads.