Open Source "Intro to Microeconomics," Price = $0
Introduction to Economic Analysis, by R. Preston McAfee, California Institute of Technology
This is a "technical" principles book, assuming a working knowledge of calculus. It will cover most intermediate material as well and could easily be used for an intermediate course; the difference is that there are explanations of principles ideas in the text.
The focus of this book is on the conceptual tools and not on fluff. Most microeconomics texts are mostly fluff and the fluff market is exceedingly over-served by $100+ texts. In contrast, this book reflects the approach actually adopted by the majority of economists for understanding economic activity. There are lots of models and equations and no pictures of economists.
Download the entire book for free here.
Buy a printed copy for $11.10 plus shipping
McAfee's Class Website and powerpoints.
Hsueh-Ling Huynh's Ec 1011a at Harvard.
Simon Wilkie's Class Website.
Roy Radner's course syllabus at NYU.
Angelo Zago plans to use the text at Verona University.
Tom Andrews' course syllabus at West Chester U.
Nicolas Schmitt's course syllabus at Simon Fraser.
Michelle Goeree's course syllabus at Claremont McKenna.
Individual chapters in pdf format.