Scratch value depends upon who made, where it is and how large.
If by someone famous, like a president (not Bush the value would go down more), value goes up and by other famous people the value will depend upon their overall public merit. If obvious and large and not shaped like an animal or something interesting but a nondescript the value will go down but by how much depends upon how many Picos are produced. If under 500 not too bad if over then it will decrease by the percentage past that point.
I hope this helps. And why does everyone just assume the amp purchased is going to be sold? It's all good.