i've been able to get a premium on rolls of bicentennial quarters on occasion. about 1.5x face for full rolls, usually. So I always hold them, too.
Walking up to a tellers window when they are in the middle of a transaction is not something you do. Change deposits are put in sealed bags in front of the customer. They are sent out to be counted and the funds are deposited into the account. The teller can not get to the silver even if they want to.
At my one branch, the tellers are VERY educated on coins, and they would've likely grabbed them for themselves... as for my other main branch, they would've definitely let me interrupt the transaction as they're always on the lookout for good coins for me.
Well I don't think anyone was suggesting you sneak up on the customer and put your arm around them. But if you are close enough to overhear the teller telling the customer that the silver value is at or near face then I don't see anything wrong with an "Excuse me but that's not correct. It's worth more than that. I'm so sure it's worth more I'd even be willing to buy it for more, if you don't mind." If the teller is like most of the ones I run into then they should be happy they don't have to sort coins/rolls. If the teller isn't happy about it then too bad for them. They were giving the customer inaccurate information and providing a disservice as a result. If anything you should be commended.
sounds really cool! Just started hunting with boxes of pennies. It takes a little bit to get over the intimidation factor. I'm on box 2. I have to figure out the return deal now. These ladies you deal with sound awesome!!!