DVDdoug:
Note that a "buzzer" or "beeper" has a built-in sound generator circuit that makes noise when you apply DC voltage and you can't change the frequency. A piezo "speaker", "tweeter", or "transducer" converts the applied AC signal to sound. You need a transducer. But, if you buy the cheapest thing you can fine on eBay it may not be described accurately.
I didn't quite get that part. I know I can produce various sounds with piezo buzzer using Tone(). Is it different when it comes to normal dynamics? If only problem is getting enough voltage to it, I could just use a separate power source and a transistor.