These are my house rules for cargo. These modified cargo rules are based on the rules in Book 7 Merchant Prince (Classic Traveller). These have been developed because the players always wanted to know what their PCs were buying. Now when the PCs wants to buy something, they first must find out if it is available. Then what type of cargo is available, and how much. Then they should use the standard procedure in Book 7. These rules can be a little modified if the planet has its own trade rules, with taxes and restrictions. The sell DM tells you the DM when selling such goods. The duty/law tells you the duty or restrictions. The penalty tells you what the punishment is if you violate the laws and are caught.
Example: The PCs wants to buy cargo at URNIAN. First they throw 2D6=6 and a cargo is available. They throw 1D6=4 and the cargo is Military Products. Then they throw 1D6=3 and 30 tons are available. (This may be split up.) The PCs decide to buy 20 tons of cargo (Military Products) for Cr. 60000.
Planet SP-TL TradeClass Price Avail D6 Qty. Type
URNIAN B-A In, Hi 3000 4+ 1 D6*10 Steel
2 D6*5 Grain
3+ D6*10 Military Products
Export rules: none
sell DM duty/law penalty
Import rules: Drugs +5 not allowed 2D6 years
Luxury Goods +3 100% fine 10*val
Military Products -2 50% Controlled fine 5*val
When coming back to URNIAN the PCs have a cargo of Luxury Goods. They don’t want to pay 100% duty so they try to smuggle this cargo. However they fail, and their cargo is confiscated and they have to pay a fine of 10 times the value of the cargo.

Foto: Martina Nolte / Lizenz: Creative Commons CC-by-sa-3.0 de
Small Cargo Rules
The modified small cargo rules are based on the rules in the Journal of the Travellers’ Aid Society (JTAS) issue #18 page 40. These have been slightly changed to make these rules easier to use. Now when the PCs wants to buy something, first they must find out what type that might be available (if there is more than one type). Then if it is available, how many lots they can buy. Then they should use the standard procedure in Book 7 Merchant Prince (except that trade class don’t apply) with the small cargo. These rules can be a little modified if the planet has its own trade rules, with taxes and restrictions in the same way as with a normal cargo.
There might also be some extra trouble with small cargoes which may lead to interesting situations. Throw 1D6 and consult the table to see if there is some problems.
Example: The PCs wants to buy small cargo at URNIAN. First they throw 2D6=5 and a small cargo is available. Then they throw 2D6-2=6 and 6 lots are available. The PCs decide to buy 5 lots of small cargo for Cr. 30000. The referee secretly throws 1D6=4 and tells the players that their PCs are delayed for 2 days. (The PCs might want to do something about this if they are in a hurry, which might cause even more interesting situations.)
URNIAN Small Cargo: Advanced Combat Rifles (6 Rifles)
Lots: 2D6-2 of 50kg
Value: 6000/lot
Type: Military, Weapons
Availability: 4+
Special Handling: None
D6
1-3 No problems.
4-6 Very strict control that the weapons aren't resold
at URNIAN. This will delay the PCs 2 days.