I was actually brainstorming a decent way to handle this, especially since the main source of money here is basically pointless due to so many various alternatives(marks, motes, strange coins) that are used instead.
I would have made a merchant that can sell these materials, but at a somewhat ripoff price. Then I would have another group that can actually go to the planets for you and get some, with various "risk" levels, the highest being most expensive and having the highest material payout. At some point if the risk triggers, it would function as an on the fly mission where a huge firefight would be happening and you would have to save them. If you ignored it, you may have paid for an expedition that never comes back and gives you nothing, or there is still a chance they make it. Maybe even have it so you can send a gun or something that you don't need anymore to drastically improve their survival if you ignore it, or additional glimmer on bodyguards.
That's just a super rough concept off the top of my head, but it's crazy that there's no alternative to straight up farming these materials. Obviously that is not everyone's cup of tea, but they can't do anything about it. Atleast the above has some potential for emergent gameplay, or can be ignored entirely(at a higher cost to feel more fair).