As PvP shouldn't be all, i have some suggestions on how trading should work.
Let's say you are exploring some planet, and you come across a interesting ore/material/etc you don't really need.
So you check it in a suggested prices menu, which changes automatically in real time depending how much of it there is in tge explored game area. So rarer items would cost more than common ones. Then in another, trade menu, you "post" items you are selling, quantity, price, and your location. Now, everyone else can see your offer, and once you are minimally, let's say 5 meters away and aren't blocked by anything, you can open up trade with the other player and sell him the item.
Now, if you have a huge freighter and lots of stuff to sell, you could search for requests in the trade menu.
If you find a request that you like, you can simply come to the requesters location, and trade him the items he needs.