The Essential James Buchanan is an excellent new primer on Buchanan written by Don Boudreaux and Randy Holcombe. It's part of the Essential Scholar series from the Fraser Institute which also includes Hayek, Nozick, Locked, Smith and Hume among others. Each book can be downloaded in entirety or by chapter and each comes with introductory videos and a guide to further readings. Boudreux and Holcombe's chapter on Buchanan on government debt is especially clear and concise. All the books in the series are written by experts, such as Erik Mack on John Locke, Steven Landsburg on Milton Friedman and Sandra Peart on John Stuart Mill. Recommended.