I didn't see this posted anywhere, but Micro Center has the World of Warcraft Cataclysm expansion on sale for $19.99 with free in-store pick-up or 5.99 shipping (ouch) making it $25.98 which is still a good price.
Link
http://www.microcenter.com/single_product_results.phtml?product_id=0345496
Link
http://www.microcenter.com/single_product_results.phtml?product_id=0345496