Been playing this game a ton in the past few days, and am enjoying it quite a bit. I have a few other thoughts about things that could be done to improve the trading system:
1) It would be great if we had a search tool for the galaxy map. When you have done a ton of exploring it can be really tedious to mouse over hundreds of systems looking for a specific factory type. The ability to add a note to a system in the galaxy map is a really cool feature, but I find it a little hard to use. Being able to search for words in notes might make it more useful / easy to use.
2) It would be nice if, at a sufficiently high quality/rarity the trading computer upgrade module would also record the number of units that the buyer is willing to buy. Sometimes it will identify a trading route for a good that the buyer will only buy a small quantity of, and if the buyer is in another sector it can be really tedious warping to that sector to check and see how many units you need to move. This should only be available at a really high quality.
3) In a similar vein to the two above suggestions, it would be great if we had an easy way to store the information on what a trading post is willing to buy/sell. I have found myself making notes in a text editor recording trading posts that sell useful and rare goods like turret parts, which works fine but is a bit tedious. Since the trading computer upgrade module already has quite a lot of features, I would propose adding a new upgrade module: a galactic database module. If this module is present in your ship, when you enter a sector it will poll the structures in the sector and record various information into a searchable database. Higher rarities of module would store more types of information. Types of information the database can store could include: what goods a trading post buys/sells, average trading ratio of a structure, actual good prices the last time the sector was visited, total number of good a structure will buy/sell, actual quantity of good present in a structure last time the sector was visited. If you upgrade the quality of your database module you will need to go back to previously explored systems to record whatever new type of information that quality allows you to record. Perhaps rarity could also affect the total size of your database: at some point you might need to delete systems that you don't find useful to make room.