if you have just started playing 0.0.72 - the dev JUST updated the game and you are playing the new version with raised curve.
I would agree it feels a bit slow right now, maybe he adds things soon? He mentioned something about this being a preparation for something bigger. but all it does is only allow me to get copper stuff now xD
Charisma, as I have seen it, seems to raise the sell price by one dollar per level, or maybe 10% of the ingot price? I did not make it to tin yet, so you know better than I do.
If it stays at 8$ for a tin ingot, this is really not how it should be, it should be a thing that is still relevant for higher ingot tiers. everything below 10 is insignificant as soon as you up the tiers