Make traders have specialties.One is food and drinks.
One is medical.
One is basic weapons.
One is basic armor.
One is advanced weapons.
etc,.
Each trader has slim pickings of goods to buy at the beginning.
Each trader offers quests based on their specialties.
Example: The food/drink trader needs resources to expand/improve their stock. They offer you a quest: Collect 20pcs of meat/10pcs of fat. You go out hunting for the animals and return to the trader and give them the items. Bingo! Trader now has an assortment of cooked meats available and gives you 'x' amount for collecting the goods but you need to pay for the rest.
Example2: The food/drink trader wants you to collect Potato's Corn and blueberries.. yadda yadda he now has a supply of meat stews and blueberry pies and berry juice. gives you a small portion of the completed goods as a reward.
Example3: He's running low on glass bottles now
he needs you to collect 'x' amount.. rinse repeat.. he gives you a package of 5 items from his wares..
etc,.
Each quest you complete for him and the cost go down but if you the player want to keep him fully stocked you need to help keep his supplies up by completing the repeatable quest. If you don't day after day his wares start to run down again.
You complete enough quest and he'll give you an option to learn a new recipe eventually or offer you a partnership and after if you check in with him he gives you a portion of the proceeds when you visit.
