The book "Junkbots, Bugbots and Bots on Wheels" offers a variety of building projects, and to make it easier for you to get started, you can select this bundle for the Bicore Headbot Project.

Included parts:
1x Octal Inverting Buffer
1x Gear Motor 3 - 224:1 90 Degree Shaft
2x 0.1µF Monolithic Capacitor
1x DT Slide Switch
2x Infrared Optical Sensor
1x GM2/3/8/9/17 Gear Motor mounts

Please note, you still require the book to build this project!