The issue is called "mark to market". Since 2008, it has been a controversial issue for financial industry / banks (i.e. the value of their loan portfolio, or mortgage based securities - if they had marked them to their then market value the thinking/fear goes that many banks would collapse, and they are still not out of the woods on that yet).
Theoretically, meiru has a valid point. http://en.wikipedia.org/wiki/Mark-to-market_accounting
But it is not unlike the cash accounting vs gaap accounting issue. When does one recognize the "hit"? In one shot immediately, or over time as heightened depreciation expense - as dmoose mentioned?
The trouble is adding that layer of detail / complexity would reduce player understanding and would probably be a challenge to implement. As the debate shows here, it would never be settled what the "true" market value is, with players arguing for their most advantageous interpretation.
Depending on most definitions, it would be a moving target and would require adjustments up and down...potentially very confusing.
In the end, that amount of realism may actually hurt the game playability, and the game community IMHO.
Besides, it appears that this is attempting to address a symptom of a different problem. Effort and resources might be better spent on the core cause(s) of the price imbalances.