Thank ferretgamer over at Racketboy for this one.
http://www.fangamer.com/products/retro-city-rampage-dx
Seems that Retro City Rampage DX is getting a supremely limited retail release of this game with just 2000 copies made and sold through fangamer.com for the PS4. The cost is $25 + your choice of shipping (I think there was 4 which started for me at $4 for USPS First Class Mail.) I ordered one as I've wanted this for awhile and a physical release will always get me to pull the trigger when the price is right.
This below is lifted from the site, there is more but this will do:
This limited edition retail version of Retro City Rampage™ DX is the rarest PlayStation®4 game ever printed! Only 2,000 available, so pre-order yours before it's too late.
This is a full PS4™ retail release. It includes a PS4™ Blu-ray Disc™ and case, factory shrink wrapped with a double sided reversible cover. It can be played on any PS4™ system worldwide, any region.
PRE-ORDER TODAY AND ALSO GET:
The official soundtrack featuring 32 tracks by Jake 'virt' Kaufman, Freaky DNA and Norrin Radd (Digital Download)
PC and Mac versions of Retro City Rampage™ DX for Steam (Digital Download)