How about we take this a step further by added something more than just an
auction house..
How about an entire new map, like the Battle Islands, that both campaigns
can access, that is solely devoted to being a merchant island.
While here, you could set up stalls, and there would be a portal that ported you into an auction house, where you could hold Auctions.
This region would both be accessable via when you either reach Kaineng Center or Lions Arch, and you could use the little ship to travel there at any time you please to do so.
Doing this would have a couple of advantages:
1. Like in so many other games, where the stalls are freely useable, it would create so much of a drop in framerate (not everyones rich to buy those nice x900's :P). In this island, There would be an NPC who would "rent" you a scroll to set up a market stall, the scroll would be realtively cheap, maybe 2-5k at max, and would last you, oh say, 2-4 hours of a stall. Why a time limit? Well, I do realize that the amount of AFK people in the servers do cause lag.. but I suppose if they're going to afk, they might as well do it decently, right? There would be a warning on these scrolls, that after your time limit is up, it would disconnect you from the game. These scrolls would only be useable at that island, saving your computer from melting away because of all the AFK'ers in Lions Arch or Kaineng

2. It would save us from spaaaaaam! I can't say my dislike twords all the spamming in the lcoal channel, even with the new patch, of people trying to sell their items. With this, they could easily set up a stall, and not have to spam a single word.
3. It would create sort of a hang-out for people. While I do realize there are many locations for people to gather and talk, people without factions, and vice versa, could still communcate through here.
4. For people who want to sell their items on-the-spot, the auction house would be accessable via a portal on the market island, saving yourself the crowd of afk'ers selling stuff. I'm not exactly sure how an auction house itself works, but I'm sure many of you who wanted one will know what to expect

While this suggestion does include some disatvantages, such as encouraging people to go AFK, thus using more server resources, I think it would pretty much be a better idea then standing around in a district with that person spamming WTS GODLY WEAPONS!! (insert all form of weapons here).
I checked around in the forums, and wether I be blind or not, I didn't see anything like this, even when using the search button, so please don't flame me if it's been suggested before

What do you think of this suggestion?