Buying a vault for the sole purpose of surviving 2012 is utterly [censored].
Having a vault for emergencies seems like it could be useful. You never know what might happen in this world. Were I ridiculously rich, I'd buy one and pretend I was in Fallout.
These things are just one step above being an outright scam.
If that's the same thing someone posted about in the Fallout 3 forum, I think only one has been made...basically by converting an existing missile facility. No others are being built until all the slots are sold.
Have any concept how long it would take to build and stock one of those things once they break ground? Maybe a year...if you're lucky, and I don't think they've started construction on any other units.
Then, if you aren't 20 minutes away from that thing when it's time to flee for the hills, odds are you won't get there until after they've locked the doors.