As for NOS, I have no idea what those parts would go for. At the last days of CTS production, I bought a few hundred to support kits while I did some R&D for a replacement speaker. At that time, all my suppliers were sold out. So while I know sometimes NOS stuff "pops up" seemingly out of nowhere, that means someone had to be sitting on the parts. To be real honest, that isn't a part anyone would have saved as opposed to having a closeout sale, so I am leery of NOS sellers. I would think it most likely that claims of NOS piezos are more likely knockoff parts sold as NOS. It's not like that is uncommon, and it even happened back when CTS was making them and selling them pretty cheap.