Food: Don't buy anything above 8, unless you are 1 or 2 days away from a place plagued by famine, then you can and will make a killing. Little villages sometimes sell food at 7 or lower. Fill'er up!

Hides: 12 or under. Often very low in small villages.

Clothes: Anything 21 and under is excellent. Price for clothes goes up in winter, down in summer. Can be tricky.

Wood: under 26 is a good buy. Beware of worms.

Tools: 25 and under is an excellent price. Beware of worms.

Liquor: under 50 is recommended.

Olive Oil: under 35, but I would stay away from that unless you have an exceptional offer at hand.

Ore: 36 and under is a good price. Very heavy, takes up a lot of space.

Carpets: 50-55 is a good range. Sometimes I buy under 60, but margins are lower. Beware of moths.

Spices: 65 or lower and a profit is at hand.

Jewelry: 75 or lower. Having a Jeweler helps pushing the price down even more and eliminates the chance of forgeries. Most of the time very cheap at the pirate island of Seech.

Porcelain: 75 or lower.

Arms: 80 or lower. Beware, they can be confiscated at times of war, and you will get compensated only a fraction of its value.

Hill Herb: under 100, only start buying when you have access to the palace, then you can sell at parties for 150+. Also it is highly illegal, you might have to bribe a few people. Not recommended for early trades.

Ice: Never traded it, but make sure you buy the freezer box upgrades, else you will watch your fortune melt away.