I'm a bit on the fence when it comes to arguments concerning undercutters. On the one hand, I can understand it sucks being unable to sell for a profit, and also sucks when people undercut by huge amounts. However, it also sucks when materials are expensive. And really, folks shouldn't be saying "Well, it'll sell at this price and keep selling at this price because this item is supposed to be this price." The rules of supply and demand do basically say that if supply of an item skyrockets (Like, say, because of people trying to do achievements) and demand plummets (For example, people powerlevelling through newbie levels and not bothering with low level gear), then prices are going to drop through the floor.
For an item to be worth a decent amount of money, it has to be both difficult to get, and in great demand. Unfortunately, the vast majority of the crap you obtain that you have to sell at a loss will indeed sell at a loss because people get that crap all the time. If you're selling items and being undercut, before you rage you should first ask the following two questions: "Why am I selling this instead of using it" and "Why would someone want this." If you can't think of a reason why the average person out there would want this, despite you not wanting it, then you probably can't expect to sell it for much.
