It may not update fast enough, but http://wantsthis.com will email you when an item in your list goes on sale on that site. You could just add all the sites you'd buy from that still have it at the normal price. (Although I've only tried it on Amazon, fwiw)
Amazon is only showing the price after the item is in your cart:
The price that is shown after it's in the cart is $493.99, hmm. And says "only 1 left in stock".
According to information given to people on deal sites that asked Amazon associates, Amazon will not be doing the price drop - they're returning all stock to HP.