There's absolutely nothing you can do as they have the right to cancel the order as long as they refund your money in full. It does not matter whether or not your card was charged. The following is stated on the Best Buy website and is perfectly legal:

Errors on Our Site
Prices and availability of products and services are subject to change without notice. Errors will be corrected where discovered, and Best Buy reserves the right to revoke any stated offer and to correct any errors, inaccuracies or omissions including after an order has been submitted and whether or not the order has been confirmed and your credit card charged. If your credit card has already been charged for the purchase and your order is cancelled, Best Buy will issue a credit to your credit card account in the amount of the charge. Individual bank policies will dictate when this amount is credited to your account. If you are not fully satisfied with your purchase, you may return it in accordance with Best Buy's Return Policy.

(By the way, I ordered 13 of those 52" LCD televisions for $9.99 myself. I, too, was disappointed when they canceled my order!)