Its already in the stratosphere in terms of value, propelled by a mega hit blockbuster movie. How can it possibly go up when the movie is gone from the theatres in a few months? If you bought it and like it, thats great, if you decide to sell, you will get a real premium for it. It is true that I'm not seeing much of these on ebay, but I do see alot of its sibling "the Dark Knight" (and I do mean alot). Which leads me to believe that there must be a similar amount of Batman Begins out there. Which in turn means that this steels price is based on hype rather than rarity, which in turn means that it has no staying power. But thats just what I think. Who knows really? Maybe it'll overthrow IM to be the new king.
For me to add any steel thats priced in the $300-$500+ range, it has to be scrutinized to death. It will be put under an electron microscope, in which every atom is examined (hahaha). But seriously, long term performance is very key for me. My collection is based on rarity, not hype.