The trend in commerce is that it will all eventually go up. Other key factors as mentioned above such as supply and demand, and the value of raw materials also make a difference.
Some ammo such as surplus x39 has gone up 60 or 70 percent in some places over the last one or two years. My opinion is that these places will slowly sell their ammo as someone will always pay the asking price, but it will sell slow, and at the end of the day, they didn't make much profit on it because their inventory dollars were tied up so long and their shelves were full of low profit items. I guess the newer shooters might pay these prices, but the remainder of us have over-gorged our own personal inventories with the low prices from 2 years ago. I need to do a hell of a lot of shooting to ever have the need to purchase this stuff again. Everyone I know is in the same boat. If the price once again becomes exceptionally wonderful, I suppose my nephews might like to shoot some when they become of age.
When dealing with surplus ammo, its exactly that. Surplus, there may or may not be anymore available. When you're talking commercial ammunition, its gone up, but not near as much as food, vehicles, homes/real estate, or gasoline, ect. If people are genuinely worried about the price, then take up reloading. The cost is a third the price for better quality ammunition.