SUGGESTION - if all UNIVERS can have access to the market whenever you put a market stand it's gonna limit all players in not being interested in going to other player made Cities ...
if you ever need something you just put one Market Stand and you got it... like this you eliminate all the interactive fun
imagine if you will need to go to the "City of Macarena" where you can find the cheapest gold and the rarest materials
-----or"City of Coco-Jambo" where you can find the fastest ships on planet X, Y , or in Galaxy.
------or "The Lost City of Ciupa-Chups" where you can find Great Misteries .
this will change the whole game. it will make it more engaging. more interesting, everything will have porpuse. at the moment what porpuse has a City? only good looks? only something to visit one time and leave it behind forever? i was imagining going to Cities and finding all kinds of MARKETS!
HOWEVER, you should be able to limit your market to whatever you want, AND if you have some kind of resources, to create a UNIVERSAL MARKET, which allows you to go "LOCO" on what is from all parts of Univers. As it is now.