The XB1 and PS4 versions of MGS Ground Zeroes officially dropped to $29.99 for the PS4 and XB1 to match the PS3/360 versions.
Amazon hasn't updated yet, but Best Buy updated. With GCU i'm getting it for $23. Although I had to manually cancel my previous preorder and order it again to get the lower price.
Figured I'd post this since nobody else has and they didn't automatically lower the price of my original order for anyone else who also had it preordered.