I saw this at my local Costco in central California this week, next to the stack of Xbox Ones collecting dust:
Even though the sign said PS4, they have Xbox 360, Xbox One, and PS3 versions available as well.
Costco usually takes $5 off MSRP for new games, but seeing $10 off on release week is a first for me.
I don't know if all Costco stores have this sale price, so YMMV.
costco.com has all versions at $55, so the $50 price is in-store only.