For making your own trade routes, here's a list of what all the merchants buy and sell:
Kalaires Plain
- Freedom Harbor
- Buying: Wheat Straw
- Selling: Wheat Bread*, Linen paper*, Cotton Cloth
- Valley
- Buying: Wheat bread,
- Selling: Salted Octopus*, Cloak*
- Ironclaw
- Buying: Woodcraft, Cloak, Fine Salt, Linen Paper
- Selling: Agaric Mushroom*, Wax Brick
- Heights
- Buying: Agaric Mushroom, Salted Octopus, Poleaxe
- Selling: Bear Liver*, Hunting Wood, Red Speckle Oak
- Windcry
- Buying: Bear Liver, Surimi, Almond
- Selling: Wheat Straw*, Creme*, Green Rum
Sea of Oblivion
- Oasis
- Buying: Puzzle Copper, Gator Scale Armor, Stone Statue
- Selling: Cyperus Esculentus*, Flint*, Scorpion Venom Gum
- Rubble
- Buying: Grilled Dry Fish, Glass Container
- Selling: Greed Reed*, Attar Paste*, Cold Flame Dew
- Land of Rest
- Buying: Attar Paste, Water Agate, Amianthus Cloth
- Selling: Crystal Chip*, Puzzle Copper
- River
- Buying: Chromatic Canvas, Cold Flame Dew, Wax Brick
- Selling: Coconut Cake*, Mastic*, Gator Scale Amor
- Towerpush
- Buying: Red Sparkle Oak, Wax Brick , Snowflake Stoneware
- Selling: Towerpush Town Fishes*, No Potion*, Amianthus Cloth
Hazed wilderness
- Damnation
- Buying:Flint,Scorpion Venom gum, Metal Platearmor
- Selling: Figuline, Pea(100), Pine(100)
- Afaesia
- Buying:Iron Machete, Silverware, Sharpedge Shortblade
Lunagrant Woodlands
- Bramble
- Buying:Mint Leaf, Meditation Spring, Water Yarm
- Selling:Butter, Woolen Fabric(100)
- Great Trees
- Buying:Ice Spirit, Pine, Papyrus
- Selling: Corolla, Wood Alcohol, Poleaxe(100), Almond(100)
- Archipelago
- Buying:Butter,Woad,Olive Oil
- Selling:Fish Sauce, Dry Cheese(100)
- Love
- Buying:Oak Moss, Pea, Sharpedge Shortblade
- Selling: Meditation Spring, Violet Fungus, Watery Yam(100)
- Scavenger's
- Buying:Olive Oil, Woolen Fabric, Beehoney
- Selling: Smoked Venison, Dried Fruit, Black Truffle(100)
Gloomy Forest
- Fairies
- Buying:Coral, Black Truffle, Lambskin Pain
- Selling: Tomato Ketchup, Wine(100)
- Windless
- Buying:Wine, Olive, Silver Ore
- Selling: Preserved Fruit, Lambskin, Silverware(100)
- Beholder's
- Buying: Smoked Venison, Dry cheese, Olive
- Selling: Alumite, Limestone, Silver Ore(100)