GameStop offers the used Red Dead Redemption for Xbox 360 for $2.99. Coupon code "CAG16" cuts it to $2.51. With $3.50 for shipping, that's a buck below our December mention of a download and the lowest total price we've seen for this game on Xbox 360. (Outside the price below, it's a current low for used unit by $3).
A close price: Walmart offers it for $6.35 with Site-to-Store pickup.