Probably the bank is selling them. I would think they would frown on a teller running their own side business at the bank.
Price isn't bad, typically coins sold like that at a bank are much higher. Back when our local bank was doing it the coins were supplied by a dealer. At that time at the dealer they were $15, or at the bank they were $28. No collector would buy them at the bank but they were a great seller to people buying them as presents for children or grandchildren who liked coins.