It’s all about the stuff - credits, goods, things. Be they supplies that a mining colony needs for survival, or luxury crystals that a rich patron is willing to vastly overpay for, the interstellar community thrives or dies on its commerce.
Unless funded by a wealthy patron, characters in Traveller will need to trade to survive. While a ship’s captain can fill the hold with bulk cargo at 1,000 credits a ton, she may be more inclined to carry trade goods. The basic procedure is that once a week you roll on the appropriate chart to see what and how much of it is available, and how much it’ll cost. Depending on what planet you buy the goods at, the price roll may be modified.
Captain Clayton, currently in port on the planet Isheah (0606), checks to see what’s available. Rolling a 54 gives the result of All Terrain Vehicles with a base cost of 30,000 credits each, and 3 are available at 10 tons each. The modified price is at 110% of base cost, so each ATV is 33,000. Since Captain Clayton has a cushion, she decides to get all 3, and to fill the rest of her hold with standard cargo. Arriving a week later in Artienang, she checks in to see what the going rate is for ATVs. Now, she has an option of going to a broker for a die roll modification (and a cut of the profits), or to go it alone. Miranda decides to go for a broker which will grant a +2 to the roll, but cost her 10% of whatever the worlds price is, whether she sells or not!
As Artienang is both non-industrial and agricultural the dice roll is further modified by +3, for a total modifier of +5. The roll is 6, which would be a mere 90% of the base cost, but with the modifier becomes 150% of the base cost, or 45,000 each! She offloads the 3 ATVs for a total of 135,000 minus 13,500 or 121,500, which is a profit of 22,500 credits on 30 tons of cargo. She probably would have been better off if she’d have just carried standard cargo.
Pressing her luck, she checks to see what’s available at Artienang. Apparently there is a large stock of Aluminum available, 200 tons of it, and for the low price of 800 credits a ton (80% of base costs). If she wanted to fill her 82 tons she’ll have to pay a 1% fee. The cost to fill the hold with aluminum is 65,600 credits plus 656 credits handling fee for a total cost of 66,256. She also has a passenger (and entourage) who is paying to go directly to Driash (0605).
3 weeks later, at the Driash starport she hires a broker to sell the aluminum. While the market is good for aluminum, it wasn’t as good as Captain Clayton had hoped. The entire cargo is sold for 106,600, with 10,660 going to the broker, leaving a profit of only 29,684.
Captain Clayton is going to need either better brokers or better cargo if she’s going to continue to speculate on trade goods! My dice rolls aren’t helping her any either. With some better rolls the profit could have been astronomical as the chart allows for up to 400% of base cost with a good enough roll, and the purchase price could be as low as 40% of base cost!