Amazon has an ongoing offer with the Vita:
Buy a qualifying PlayStation Vita console and receive a $50 promotional credit toward the purchase of items shipped and sold by Amazon.com
This is not a big surprise since some stores in Europe and Japan got similar deals recently.
So, this is not a 50$ discount on the Vita, but basically gets you one or two AAA games for free (I’m thinking Gravity Rush or the new Assassin’s Creed) on the console, quite a good deal.
Check the Amazon page for details.
(disclaimer: I do get a percentage of the sales if you click on these links. But you don’t pay anything more)