Frys.com has Planet Earth Complete Series on high-definition Blu-Ray for $14.99 with free shipping. It's on back-order, but they are still taking orders.
Limit 1 per Household.
(when purchased between 11/23/2012 and 11/29/2012)
The product description does not say Blu-Ray, but the UPC matches the BBC Warner Blu-Ray version.
"This product is currently not in-stock in our fulfillment center. We are accepting orders for this product, but we do not have an estimated arrival date. Our buying team is working diligently to obtain this product from our supplier. A credit card authorization will be processed when your order is placed. However, your credit card will not be charged until the product is shipped."