Basic concepts
A merchant’s group Expertise is simply the total of the group's best Trade skill, Connect skill, and the better of their Intelligence or Charisma modifiers.
The Connect modifier has two limitations:
1. It cannot exceed the group's best Trade skill;
2. If they have absolutely no previous contacts or trusted partners in the planet, they suffer a penalty of -1 to their Connect level, for a minimum of -2.
A group can pool their talents to use the best numbers available to them in each skill or attribute, but this requires close cooperation and trust. Any member of such a group can easily cheat the others in ways almost impossible to prosecute under ordinary commercial codes.
Moreover if another player character that's not part of the group wants to Aid that trade, the player first describes what sort of action they are taking to help their comrades. They cannot use Trade or Connect skills to Aid. If the GM agrees that their effort makes sense and would be helpful, the player then rolls a relevant skill check against a difficulty determined by the GM. If it’s a success, the group gets a +1 temporary bonus on their Expertise. Multiple PCs can try to help, but a single transaction can’t earn more than a +1 total Aid bonus. NPCs cannot Aid.
Cargo is characterized by its Types, a set of descriptors attached to the specific load of goods. Types describe the most salient characteristics of the cargo- the fact that it is Postech, or Medical, or Agricultural, or Mineral, or Maltech, or Luxury, or so forth. A load of metawheat might be both Common and Agricultural, for example, while a shipment of spike-3 drive cores might be Rare and Postech. A cargo’s types influence its salability on a world. An industrial planet will be eager to buy Agricultural and Mineral inputs, for example, while a primitive farming backwater might pay dearly for Postech, or a decadent space station for Luxuries.
Every world has some measure of Friction, a score indicating how much of a far trader’s profit is going to be eaten up in taxes, extortion, payoffs, bribes, protest insurance, and obscure yet costly local customs. The higher the Friction, the harder it is to turn a profit as the locals siphon off more of the take. Friction usually ranges from 2 to 5 depending on the commercial friendliness of the world. Adventures and In Character actions can change the Friction of a specific trade.
Finally, every world also has a Trade table, a list of ten types of cargo that are often worth exporting, with their base (galactic) prices and local supply and demand modifiers. Other goods might be available at the GM’s discretion or as part of an adventure, but these ten goods are the ones most significant to interstellar traders. When a PC trader looks for something to buy, he rolls twice and the GM checks the trade table. The results indicates the two commodities with the best prices at the moment. If he doesn’t like either, he can push for more marginal deals, and reroll both dice. The Friction for that sale goes up by 1, however. He can repeat this process as often as he wishes, but each reroll bumps the Friction 1 point higher for that particular sale, as he starts cutting worse deals to get what he wants. A trader does not need to roll on the trade table when he is selling goods; only when he seeks to buy the local products. Finally, planets cannot supply an infinite amount of goods to a merchant. The GM has the rules and limits for that.
If the trader does decide to take the deal, the GM then rolls 1d10 to determine whether or not some Trouble has struck the bargain. Different worlds have different trouble thresholds; peaceful and trade-experienced planets might give trouble only on a 1 in 10, while a battlefield world ruled by rapacious warlords might have a 5 in 10 chance of difficulties. If it is equal or less than the trouble chance, then something unfortunate happens in the course of the bargain. Portions of the goods may be lost, Friction might spike for this particular deal, or the business might be delayed by some weeks. The troubles can be diced out with no great investment of player's time, but if the PC cannot stand to endure the loss a suitable adventure might reverse the charges.