Amazon only charges once the item is shipped. if you pre order and the price lowers from the time you pre order it, and the time it's released, you will pay the lowest price.
however the way they ship, amazon.ca, amazon.com and the worse of them all amazon china(they simply packed 5 steelbook on on top of each other and shipped it like this with steel book pilled up against steelbook, guess what kind of surprised I had when i opened the box ?) so far when I order 1 item, which I do often, the BEST wrapping I've see is Amazon UK. I ordered a steelbook and they were all prepack is square boxes with a soft plastic holding the steelbook in the small square box all sealed up and they put it in a cardboard envelope...best wrapping experience from Amzon. I've heard horror story about amazon japan shipping the steelbooks straight in a plain cardboard enveloppe
PS: that was my personal experience, doesn't mean that it is always like this.
