In many ways, this subsystem helps generate short adventures for your cargo-hauling PCs since there’s always a chance of something going a little wrong. At the very least, the system works hand-in-hand with a sandbox-style campaign, as the PCs travel from world to world looking to buy low and sell high!
The free trader archetype (Starfinder Character Operations Manual 103) is an excellent choice for a character in a campaign focused on galactic trade. The merchant savvy ability can be used with these rules as follows.
Before beginning a game using the galactic trade subsystem, make sure your players are interested in engaging in the life of freelance merchants. While it might not seem as glamorous as delving into alien ruins or fighting back against an evil empire (though galactic traders can still undertake such adventures), this type of campaign has its appeal to certain players. Generally, merchant PCs aren’t beholden to any one patron and can go where they please. However, if your group doesn’t seem keen on the bookkeeping required, it might be better not to use this subsystem!
On average, the PCs will need to complete three to four cargo transport jobs
to gain enough BP to upgrade their starship to the next tier. As the group advances
in level, they might need to complete a few extra transport jobs per tier, depending
on their market savvy and whether or not they’ve switched to a larger frame
that can hold more cargo.
Of course, during this time, the PCs should earn XP in the usual ways (by overcoming skill-based challenges, defeating enemies, and earning story-based rewards) so that the group’s APL keeps approximate pace with the amount of BP they can invest in their starship. At your discretion, you can reward the PCs with XP as if they had overcome an easy encounter (Starfinder Core Rulebook 390) upon selling their cargo; you should add this XP to any XP they earn from encounters that emerge from complications.
This subsystem assumes that the PCs earn their BP only from transporting and selling cargo. However, at your discretion, you can reward them with BP as treasure from particular encounters (such as a raid on a smuggling operation’s warehouses) or as salvage from starship combat encounters (such as a fight against a rogue Corpse Fleet ship). In the former case, the PCs have to transport the BP to their ship much in the same way as loading cargo (count a cargo lot as 4 BP for these purposes), and in the latter case, the PCs can earn a number of BP depending on the enemy starship’s size category (Tiny = 1, Small = 2, Medium = 3, etc.).