MooseKnuckles
CAGiversary!
Just like the title says, it's the cheapest I've seen for a physical copy. I know it's been free is you have PS+
http://www.amazon.com/Gravity-Rush-PS-Vita/dp/B0050SW1WW/ref=sr_1_1?ie=UTF8&qid=1372515669&sr=8-1&keywords=Gravity+Rush
http://www.amazon.com/Gravity-Rush-PS-Vita/dp/B0050SW1WW/ref=sr_1_1?ie=UTF8&qid=1372515669&sr=8-1&keywords=Gravity+Rush