Undercutting by alot is a decent way to lower the prices. People in general are impatient and therefore wish to sell their wares as fast as possible, so by undercutting by a lot usually makes them undercut you again and your price will become the price level for that particular ware. To give a theoretical example: Leatherworking leg enchants currently cost approximately 1000g each. If I post several for 500 someone will most likely try to undercut myself with the new price of 499g. Another would end up undercutting him again and the marked would stabilize on that price range. Now before anyone comes with the claim that people would just buy the undercutting wares and repost them, I would like to say that from my experience happens rarely due to the fact that most people is unwilling to spend a larger ammount of money on wares they can craft themself or they simply lacks the funds to do so.