Its this reason why I think ultimately the auction house system should be implemented.
Several ideas I have to regulate the auction house
1) Make all auction houses independent from each other (1 per faction and only in their capital city). One universal auction house totally tanks an economy because bots and hackers flood the market with items slightly above vendor value.
2) No cancelling auctions early. Once its for sale, its there for the duration.
3) Add a hefty listing fee to discourage flooding of the market, but lower the selling fee post purchase.
4) Possibly add a restriction on how many items each account can list per day. (25 per day?) That way people arent selling 1000 iron ore in stacks of 1 for slightly above the vendor value of the item. Again, prevent flooding of the market, bots, and in some small part the hackers too. Make auctions more meaningful. Also prevents people with a lot of money from cornering the market.
Let the rage responses begin!