To acctually have an IG location to run a shop (like the orc bashers currently have) you must submit and create a guild which may later be allowed to open an acctual store.
There are a number of rule about submiting a guild such as the founder must be level 12 or higher (I think) and you must have at least 5 interested future members to submit. There is also a fee of gold for submiting and any property the guild will purchase will also have to be payed for. This can cost between 100-200k gp depending on what you do.
You will most likely only be able to have one "store" location if you follow through to that point. Though you wouldnt really want more as it would be difficult to staff. one in every city would be impossible to staff, and there arent enough players spread throughout the world to require that kind of a real estate presence heh.
Note: I just breifly outlined some of the rules, and my listing is by no means guaranteed to be comprehensive or accurate. Please look up the rules for guilds by searching for them on the site.
-TV
Edit: Star Traders has kinof a sci-fi futuristic feel to it. Even though theres nothing "wrong" with such a name (its not like stars were recently invented heh) the sci-fi pop culture has kindof tainted it, especially since it almost looks like "Star Trek". Something similar but without that exact wording would have a tone and feel more appropriate to the setting.
Such as:
Full Moon Trading Company or Full Moon Caravans
The Twilight Traders (though this one sounds like a cover for a thieves guild heh)
Even "Bright Star Traders" loses the sci-fi connotation, or "Blue Star Caravans"
Feel free to rip any of these off either directly or alter them to something you like better