Ok let's start
As I said in a Psvita review page, this is one of the misses Sony made with PS vita. And those are this overly priced memory modules. Let's look at the prices:
4GB - 27€
8GB - 42€
16GB - 65€
And you must use those exact modules for PSvita. Sony said that's an anti-piracy measure, but let's face it, they want to milk the money as much as they can. Shame on you Sony. And what happens when hackers manage to play backups form your own modules like they did with original PSP?


