Ran across this video while searching for something else. This is a great project for a parent and their child to build together! Very simple, straightforward and inexpensive. If you want to build a stereo amp, you'll need to buy two of everything. Radio Shack may have most of the parts...may. However, you can also order from Mouser, Jameco or Digi-key. You can use a speaker with a higher impedance, like 10, 12 or 16 Ohms but not lower (6 or 4 Ohms) as it will badly distort. The author does a great job of going slow, step-by-step through putting the components on a breadboard.