Letter of Authorization to Charge Credit Card

I authorize Collector's Paradise, Inc. to perpetually charge to the following described credit card the amount equal to the value of product I have agreed to purchase, until I notify them to stop. The amount I shall be charged, whenever appropriate, as agreed, shall be equal to the total retail value of the product I agreed to purchase, minus any discounts given to me at the time, plus any applicable sales taxes and/or shipping amounts.