How about, although this may cost some money, a trading resource very similar to Team Fortress 2's backpack.tf where you can vote on prices, add a trade list, etc... As the trading system is very disorganised, only the most experienced traders get pricing and profit and there are alot, alot, alot of people complaining about scams because they do not know the price of their own item.
Tell me what you think, good idea, bad idea, maybe needs some modification? I think it's a great idea and will help a large proportion of the trading community.