Anytime I have done an early listing preorder with amazon, they kept the prices. (USA Amazon that is)
That's how I got Uncharted for the vita for 40 dollars at launch. I always check though before they ship to make sure they are still listed for that price on my orders page. That's just my experience with them though.
Had Darksiders 2 been one of the titles they listed, I might have preordered that. Not really interested in what's listed there right now though. Still was fun to browse through though.