Markets fluctuate for everything. Prices go up and down for all sorts of goods depending on supply and demand. It is simple mathematics. If you have more of any particular good then you can sell then that will inevitably drive down the price of that good as you try and sell it. If demand is higher than supply than you would be comfortable putting up the price of that products as you know that chances are that you will be able to get more money for it than before. Also you will be keen to sell it for more because you know that when you go to replenish your suppliers there is a chance that it will cost you more to replace them.
These are the economic fundamentals that every company and indeed individual needs to live by. Obviously companies need to make money and individuals need to survive. So they nee to keep track of what things cost such as EVA Mats and Foam Mats. Just like any other product the price of EVA mats and foam mats is determined by supply and demand. If the factories are producing more of these training mats than the market requires then the price will fall. If they produce less then the opposite will happen. The chances are that the factories will only produce mats when they are sold so this will rarely be why the price has moved.
The other factor effecting the price of manufactured goods such as EVA mats and foam mat is the price of commodities. If the price of the inputs materials goes up then this will effect the price of the finished product. So for example the price of oil might effect the price of EVA mats because EVA is a petroleum by-product and therefore is tied to its price. Other things that might effect it are currency fluctuations. As most manufactured goods made in Asia are calculated in USD, should its price change compared to the Aussie dollar then that also could have an effect.
So as you see when looking at the price of EVA mats and foam mats it is clear that they are influenced by many factors. The moral of the story is that if you see them fall in price and you need some then buy them then and there.