For the last couple of years, every time I was in Walmart, I'd pick up a couple boxes of 9mm, 223, and 22lr.
I originally started doing this because of hearing after 2008, ammo prices never came back down. When I saw Federal 9mm for $9.47 a box, I slowly started stacking. Before Sandy Hook, that price, in just 2 years, was now at $11.97 for the SAME box. We are talking about a $2.50/per box increase in less than 2 years.
My hoarding isn't to fight off the mobs of people should a SHTF situation occur -- but to lock in good pricing on ammo that I will eventually use some day :) Not many investments have increase over 25% in 2 years :)
I've never seen ammo drop in price, and probably will never see it drop in price. 10 years from now, I'm sure we'll be lucky just to find 9mm under $25 for a box of 50 :)