For non PS+ subscribers it's not (as) much of a deal. Cheapest physical copy is $31.96 + $2 from VideoEzy. Some people prefer digital copies though, for example; to share on 2 different consoles.
Copy + paste blurb:
What if our greatest heroes became our greatest threat? Injustice: Gods Among Us introduces a bold new franchise to the fighting game genre from NetherRealm Studios, creators of Mortal Kombat. Featuring DC Comics icons such as Batman, The Joker, Green Lantern, The Flash, Superman and Wonder Woman, the latest title from the award-winning studio presents a deep original story. Heroes and villains will engage in epic battles on a massive scale in a world where the line between good and evil has been blurred.
In case there is somebody else out there interested in this….
The Battle Edition is pretty cheap at the moment if you already have an account with Gamestop. Can be a pain to setup as I needed to "fax" them proof of my bank account when I bought this pack from them a few months ago.
I used this "free fax" site to send it.
http://www.gotfreefax.com/
It's $99.99 US, but if you use the code 10FWT, it takes another $10 off it, so $89.99 + $35 delivery = $125 US.
http://www.gamestop.com/ps3/games/injustice-gods-among-us-ba…
This pack was only ever sold in North America. It's the same price for the Xbox as well.