The important line between good "stockpiling" and bad "hoarding" is not the occurrence of the event being prepared for, but rather the point where the normal price/demand relationship breaks down. People who started buying up ammunition in May of 2007 would have by their actions served to encourage manufacturers to produce more than they otherwise would have--a useful function. People who are buying in May 2009 have no such effect, because manufacturers are already producing all they can. Further, while rising prices normally serve to discourage people to refrain from buying things they won't need immediately, the scarcity of ammunition is causing to people to buy ammo if they think they might need it, even if they otherwise would not do so.
You’re too hung up on this from an economic business model point of view.
Look, people are not ever in the same place in terms of preparedness, or thinking about how much they need at a given time. People come to the game late, some come early. The people in May 07 are early, the ones waking up now are a little late. But the market adjusts prices for it.
And there are other factors besides jsut wanting ammo that are driving the prices up. Foreign demand for metals is higher than it has been in awhile.