Ebay has knack on ps4 for 39.98..personally im waiting till the price drops as the game didn't get great reviews but a lotta ppl are using their target 30% off coupons on this game and might want this game to play with their kids on ps4, so this way you could just save your coupon for something else or not pay the full 60 bucks for it.. seems like the seller has good ratings as well.
http://www.ebay.com/itm/Knack-PS4-Brand-New-Sealed-Playstation-4-Video-Game-NTSC-US-Stock-Free-Ship-/161150666015?pt=Video_Games_Games&hash=item258554051f
http://www.ebay.com/itm/Knack-PS4-Brand-New-Sealed-Playstation-4-Video-Game-NTSC-US-Stock-Free-Ship-/161150666015?pt=Video_Games_Games&hash=item258554051f