In a competitive market, prices tend to fall to the zero profit point. Of course nobody survives on zero profit for long, so that's not exactly the reality, but it is the pressure. If an Item becomes cheaper to produce, and Company A and Company B both produce the item, one of them will drop the price to get more sales at a slightly lower profit per Item. And back and forth.
That's just the theory though, if you look at the videogame industry, the prices keep rising and lazy productions are more expensive than ever (e.g. oblivion remastered).
Same goes for my movie theater, when did it x2 its price in the past 5 years while having less employees ? Oh wait, there's only one theater in town and I don't have a car, that's probably why.
