I've generally found that cancellation is quite possible so long as the item hasn't been sent yet, or isn't about to be sent. This is even true in cases where I've tried to cancel online, been denied because "the order has been sent to the warehouse for fulfillment." All that is required is to give them a ring, and they'll cancel it for you. Do you have Amazon Prime, and is the item Prime-eligible? That can have its advantages as well.