Looking to go electric on the cheap? In this video tutorial, you'll learn how to make a contact microphone out of a Piezo Transducer, available for $2 from Radioshack (part #273073A). You'll also need some sort of audio connector, which can either be salvaged from old electronics or bought from Radioshack as well. This video also covers how to make shock mount for the mic out of scrap styrofoam. Amplify most anything with this how-to.