If we could create our own shops, selling stuff would be ALOT easier than using trade, since you can set up your own in haven. If the player clicks on the stand, one of things can happen depending on if the player is there or not. If the player (The merchant) is there, the other player (The customer) can tell what they'd like to buy. If not, a robot merchant will appear and replace the REAL merchant until he/she gets back to his/her shop, witch can be toggled on & off. The player (The merchent) can customize the options for the shop (EX: Customize item categorys, edit prices, toggle an option for a merchant robot on & off *For is the merchent isn't there* & what type of currency is needed *Like tokens, certian material, and crowns*). Shop stands come on 3 sizes depending on how much energy you used. Small saves ALOT of room for other stands, normal takes a bit more room, and big takes ALOT of room. The stands are also portable, witch lets you take them around, and use them in different places (Except the clockworks, unless you can prepare for the next floors, & the training area). It COULD make getting tokens, crowns & materials like as IF your doing a job in real life.
You do realize there is an auction house that handles most of those functions, without cluttering up the place?
The problem I see with your idea is the space taken and the amount of players. If push comes to shove, this'll end up like in FFXII, where there were oodles of instanced "market stall ghettos". And you had to click EVERY SINGLE ONE to find the item you were looking for, making shopping and excrutiatingly slow and painful experience.
So, thumbs down. The Auction House handles that issue with a minimum of muss and fuss.