That not how supply and demand actually works. In ideal world yes, but you have market manipulations and other "tricks" that can very the price ridiculously. There the old truth that a player wanting to corner the market on items always buy items cheaper than hes selling them for and restocking AH with "new" price. He then uses a mule to "buy" the item at the prices several times "raising" the cost.

For example, NI goes anyway from 150k~800k or more. S this "normal" supply and demand. In the real world if a person was the only one selling milk and started charging 1million for it, how soon before his store would be burn down, his eyes plucked out, and his body hacked to pieces?