This how-to book is really well done. In the first several chapters, it presents short conceptual descriptions of the capabilities that will be implemented in the robotic software, and walks through the robot assembly process thoroughly. The author describes two robot platforms – a 2WD robot with caster, and a 4WD skid-steer version. Both are available in kit form for under $200 on MakerShed.com (search for Rovera). The kits seem to be the way to go; a link to a parts list is also provided.
After the sections on robot assembly, the author walks the reader through a series of programs that illustrate increasingly sophisticated capabilities of the platforms – speed/direction control, sensors, edge detection, autonomous movement, etc. The software presented is clean and well-organized; the author also describes the examples, and provides troubleshooting tips. (Links to Arduino / programming references are provided).
In summary: the book and the Rovera kit(s) provide a low cost, hands-on introduction to Robotics.
(Disclaimer: I participate in the O’Reilly Blogger Review Program).