Mmm, whether or not there is a price history, the price of the items are determined by the time it take to bring the items to market and the demand for the item. I think the only useful place for a price history is determining the relative value of an item when there's no comparison to be made.

In addition of the price history, you could put up a scroll on the wall (which would change with the economy) with set prices of what SE thinks those particular items should sell for
Never ever going to happen and for good reason. Aside from it being entirely useless, it's entirely arbitrary. SE can hardly control the supply of items and certainly could never control the demand for them. The actual value of the items would float around and it would only be a reaction to these changes that some determination could be made. It would be better to implement an FFXI price history than to have something like this.


Even with abuse, items are still, with few exceptions, sold at prices that channel the scarcest items into the hands of the richer and the most plentiful to everyone. A price history just gives people an excuse to be abused or to use less than rational decisions, and, in the end, simply hurts rather than improves the economy.