Best Buy offers The Killing: The Complete First Season on Blu-ray for $9.99 with free shipping. (It's on backorder for one to four weeks, although in-store pickup is also available if you can't wait to find out who killed Rosie Larsen.) That's the lowest total price we could find by $25. Sales tax is added where applicable. This set includes all 13 episodes on three discs.
Update: Shipping is no longer available. You can still order it online for in-store pickup.