Currently, Discovery Store is offering the Planet Earth: Pole to Pole, Mountains and Deep Ocean DVD for just $4.97. Use code SAVE5 to save $5 off your purchase, making it only $2.95 for shipping.
You could get this Best of Discovery Collection Volume 5 (4 Disc Set) for $2.95 shipped as well.
**Go through ShopAtHome first and get 5% cash back.