How do you, devs, want the market to look like? I always wanted To see a real market with lots of player created stands with adverts everywhere or even outside the market. I mean that nowadays each MMO has just an auction house with few NPCs and the trading is automated, we don't even know the trader. On the other hand, we can just stand somewhere and shout what do we want to buy/sell or use some global trade chat and then use mail - but those are present in every game aswell. It could be alternative for those who can't afford renting a market stall yet.
I know, that would be hard to implement such system to a game, the stall area would need separate realm, and some area renting system for sellers. The area would have to be large and divided into different stuff type zones etc., etc.; but wouldn't it be original and genuine? Okay, such solution is already done in Second Life, but I've seen no fantasy MMO with similar market.
That would also force players to build their stalls attractively enough to make some people come and buy. Oh, and it could be somehow connected with the player isles. Maybe the custom stall itself could be built on those islands? Allowing players to leave trading offers active even when they are offline but making them more attractive than just single auction house with tons of offers.
Well, think it over, such market would be something new