Go on-line and find spot metal prices - looks like tin has been trading $US 14 to 15 per pound over last few days. I expect that is for pure, foundry certified stuff - no idea what minimum quantities are traded to get those prices. No idea what your sample shown is - how pure? How was that established? I have not bought or sold metal at scrap dealer, so I suspect you would get significant less than spot price there?
I do not know how to identify some metals - would be very hard for me to say this is pure tin, versus this is pewter. I do not know how to tell the difference.