Target offers Hansel & Gretel: Witch Hunters on Blu-ray / DVD for $4.50. (Amazon offers it for the same price with free shipping for Prime members.) Opt for in-store pickup to avoid the $4 shipping charge. That's the lowest price we could find by $2.

Update: The Target item is no longer available for store pickup; however, the Amazon offer is still available for $4.50 with free shipping for Prime members.