An item is out of price for a few days? Okay. A week? Maybe. What about three years?
I don't think that anyone who has spent some time buying and selling items on the Grand Exchange, at least in a non-whimsical manner, would accuse it of being a perfect system. However, in order to understand what is "wrong" with it, one first needs to know how it operates.
The purpose of the Grand Exchange is eliminate so-called "transaction costs" between a person selling and another person buying. In other words, if you want to buy a rune 2h sword, instead of standing in a certain area spamming that you were doing so, you simply place a bid on the Grand Exchange and let it do the searching for you.
Naively, you might hope to draw up this system and call it a day. Unfortunately, it's not nearly that easy. Firstly, some sort of guide is needed to give people a rough idea of where to buy and sell. Imagine if all guide prices were wiped off the Grand Exchange tomorrow and everyone had to choose everything essentially from scratch. Although some part of me is tempted into thinking it would be fun (perhaps lucrative!) to watch all hell break loose on the G.E., it does not seem to have the best interests of the general RuneScaper at heart. So guide prices must be set, which is left up to Jagex.
Several factors make setting an initial price for a (new) item difficult. First of all, it's difficult for anyone to guess what the price of an item is going to be or should be. Even the developers of the game were surprised at first by players' apprent preference for experience over money. Then there is the novelty effect: everyone wants the new thing when it first comes out, which will inevitably drive up the price in the short term. It's also often in short supply at first, before more are created. Take corrupt dragon for example - a new, more powerful weapon available for F2P and only cost-effective for PvP situations. At first, anyone with a few million to spare wanted one to try it out and pushed the price up, but soon enough they crashed back to almost nothing. They are higher now thanks to Evolution of Combat, but that's a story for another article.
Obviously the value of an item can change over time. What happens to the guide price when it does? Due to the nature of people panic selling or buying, the price of an item often rises or falls faster than the guide price can keep up. Such changes are capped at 5% up or down in a day, for most items. However, transactions occurring above the guide price is still not enough. There is a second criterion: namely enough volume must be generated, and until that magic quantity of said item has been bought and sold through the G.E., the change will be 0. When this happens, we end up with something like this. The rising price of the soft clay used to make them, also shown on the graph, only worsened the discrepancy between real price and guide price not being able to catch up. I had quite my share of fun with those prices all that time ago - leaving a buy offer for ~100 on a noob account to collect urns two or three at a time, and then selling them for 10 or 20 times the price. I had no use for the money, but it was clear what was happening: market price was much lower than the true value.
Making urns is okay crafting xp but it's not exactly Jagex's gift to Runescape kind, so aside from a few people dumping urns on the low-volume G.E. market, there is demand, little supply, and prices take forever to trend up. In addition, the cost of making urns, two pieces of soft clay, exceeds the current price of almost all f2p urns, so there's not much profit motive either. Of course, you can mine your own clay but with opportunity costs factored in it's exactly the same dilemma. I might add that as a semi-regular purchaser of said urns, offers often fail to complete instantly even after mashing +5% several times - something that you would not expect from any item near its equilibrium price.
Of course, when prices are out of date, it brings up other issues as well. Players will trade those items as cash, and the value under wealth transfer shows up as so. For example, if I have a weapon worth 10M according to the guide price but actually worth 5M, another player may be mislead by the guide price and be very eager to buy it off me for the "cheap" price of 6M. Is this a scam? The dictionary defines a scam as an act of deceiving people to make money, but in this case it's almost as if the G.E. is committing the scam.
I'm not particularly sure of how to "fix" these issues. If wider price fluctuations are allowed, wealthy individuals and merch clans will do their best to take advantage and wild price oscillations will be a likely result. Perhaps some system which operates at least partially on an average over the last several days could be more desirable. Maybe the G.E. needs to provide more updates even if volume is low or nonexistent. If you have other ideas or suggestions, I would love to hear them on the discussion thread.