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Each successful trade improve reputation with station owner faction. Gained reputation proportional to transaction value. You need to trade goods with cumulative worth about 6 000 000 000 Cr to gain 30 relation with faction.
Manual trading (and mining) overlaps with the related 'ware shortage' missions. They are a bit bugged and the source of on-going investigation by Devs but in the meantime, the guide here can help.
Personal trading via Skunk
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