Riley - Do you actually have the knife in hand yet or has the system simply processed your order? This is most likely an error and I'm virtually certain that the merchant will not honor any orders placed at that price. (They are certainly not obligated to.) What usually happens when something like this happens is they will contact you and tell you that the order has been cancelled. Just because you clicked on it doesn't make it a binding contract. At the most basic level, a contract requires an offer, acceptance and consideration. Paying for shipping alone will not cut it for consideration.
As ashtxsniper said, it could be a promotional "loss-leader" item, but they would usually say so and state right up front that there was a limit.
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