Answer:
It's anything but amusing when this body part gets hit.
I am the tool, for inspiring many. Buy me in the store, for not much more than a penny. Don't overuse me, or my usefulness will go.
Many hear me, but no one sees me, and I only speak when spoken to
Pirates put their booty in it.
You saw me where I never was and where I could not be. And yet within that very place, my face you often see.
I repeat only the last word you say. The more I repeat, the softer I got. I cannot be seen but can be heard. What am I?