Evidently, more than a few people were totally disappointed about the price of the iPad Mini and the extremely low resolution of the Mini's display, and decided to go with something that has both a higher-resolution display and a lower price.
http://www.businessinsider.com/amazon-kindle-fire-sales-after-ipad-mini-2012-10
http://www.businessinsider.com/amazon-kindle-fire-sales-after-ipad-mini-2012-10