I just don't understand how the NSA can even have the technical capacity to store all of this data. If their total operating budget is a few billion dollars, that doesn't even really come close to buying enough disk to store what some claim they are storing (all network traffic, social data, images, emails, voice, etc).
The best speculation I've seen on the matter is that the NSA's budget is between $12 and $15 billion, but that was several years ago, it might be much higher now with the emphasis being placed on all of these programs (with the NSA effectively being turned into a military asset).
We can extrapolate a floor on their budget by looking at the FBI and CIA, with it being publicly known that the NSA is far larger than both.
The FBI's 2014 budget request is for $8.4 billion, with 37,000 permanent employees. The NSA is thought to be at least two to three times larger than the FBI.