I dont take pleasure in saying this but, the real "negative force" behind high pricing are the gamers that keep buying the items.

Anyone trying to make a profit (much like most of us on the in-game market boards) will try to pass off the highest price possible.
If no one buys over a long enough period of time, we will likely lower the price.
If even one fool buys, we will forever know that even though the price is high there is a chance it well sell at that price...and keep selling at that price in the future.