Can someone explain the trading mechanics?

[Comrade Johnny]

Recently I have decided that I should go shopping (alright im broke and need stuff to upgrade the ship) and I realized that there are a lot of numbers that I do not exactly understand. For example, grasshopper tech has 856 trade volume, what does that mean? Just an index about the places they own and sell resources at or is it something concerning me?
The credit is more straightforward, but my question is: How do I get it? "Selling" things just trades them for items of equal value they sell at the station and credit is freely usable. Do I just have to keep running missions for them?
Thanks in advance, the game is a bit intransparent

[Commisar Jon Fuklaw]

Trade volume is the credit value of goods you have bartered or traded with a faction. Bartering is done if you have under 25 reputation with a faction, trading is unlocked at 25 reputation and you get better exchange rates up to 100 reputation, wherein you get 25% off of all transactions. Yes, this can be used to get infinite credits/items if that's your kind of thing.

[Comrade Johnny]

Originally posted by Commisar Jon Fuklaw:

Trade volume is the credit value of goods you have bartered or traded with a faction. Bartering is done if you have under 25 reputation with a faction, trading is unlocked at 25 reputation and you get better exchange rates up to 100 reputation, wherein you get 25% off of all transactions. Yes, this can be used to get infinite credits/items if that's your kind of thing.

Ah thats nice to know. I was honestly just looking for upgrade modules and components since missions drop that somewhat rarely. Actually they dont just the ones I need are seemingly ultrarare when I need them. I was also hoping to trade item chips since the droprates are... low. But I was mostly wondering what I was supposed to do with my like 18k store credit for grasshopper tech
Thanks for the explanation