So in space stations there’s this thing that looks like Wheatley from portal. You can also buy and sell from the ships that land

High tier economies (3 stars, which you can see it when you’re in the system or if you have the economy scanner) will have more items which means an increase chance of the item you want

As for ship building (which is what I assume you mean by ship parts) you have to scrap ships. So either find a ship you own or buy one from the npcs that land and you can salvage ONE part from it then recombine it with other ships you salvaged. For fighters I think it’s engine, wings, and body

I’m kinda rusty cus I haven’t actually made my own ship and I’m haven’t 100% memorized the layout of the new stations and I really only play during the expeditions (time limited events)

If you have questions feel free to make a post. We would be more than happy to help a fellow Traveler