The game world is very large, and players are split into Shards, so no this wouldn't be a problem.
Also, the portable vendors would have no collisions, so you couldn't jump on them or get stuck by them either and they would look a lot smaller than a normal vendor, they would be like the size of a current ammo crate.
Lastly, you would not be able to sell items to these vendors, they would only be used for selling your own items to other players.
i just think this idea is brilliant ell you have my support on your idea
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This whole idea brought me back to days when I played FlyFF and Cabal. A shop was basicly a skill. You could open your shop anywhere (later on it became towns only, and there was always at least 1 server where everyone went for selling their stuff, LAAAAAGGGGGG), but in the meantime you couldn't move your character. So all you could do was chat. People made special alts for this. However, since I wasn't able to use the computer basicly 24/7 back then, I never really had the time to do so. But as annoying as it was, I would prefer such a thing over an Auction house. (Without the "you can't do **** in the meantime" though)
^That is basically the main problem with this. In other games where this actually is possible people tend to congregate in high traffic areas to maximize their sales. No one will set up a shop in some desolate portion of the map.
And yea, the different shards would help with clutter. But, at the same time it would inhibit your potential sales.
Other than that i support this idea, or anything really other than just person to person trading.
If I remember correctly Aion has a similar thing where people can create their own store and sell items they have found. I think it would be a pretty neat feature. I could see this turning places like Iron Demon Ranch into major hubs for the game.
I agree, there's plenty of space in Iron Demon Ranch for market stalls.