Order cancelled, trust lost.
I have placed orders with you in the past and had great experiences. I placed an order this time, and supposedly the price was listed in error, so my order was cancelled. Had the price been listed in error in a way that benefited your company I doubt the order would have been cancelled. Regardless, if the price was listed incorrectly or not you should honor the purchase I made. I am planning on sharing this experience with a coin collecting group with over 250 members, so they will also think twice before ordering with you in the future.