I've bought the Game yesterday and haven't played only two short games until now but I have one idea that make buying mods for weapon much more easier.
Would it be possible to show in some kind of way the available mods for a weapon in the mod menu and if you try to buy it and it is available on a trade you click on it and connect directly to the trader that shows you what you need for this kind of mod?
That would also fix the problem that you always know what weapon mod can be put on which weapon.
As I said I have the game only since yesterday but that is one thing that I noticed very quickly
I like the game very much and it has so much potential.
Keep on guys this will be the next big thing