There are a handful of traders who have settled in Chernarus looking to make a fortune. A good old fashioned crises always seems to yield rewards for the lucky ones.
Luckily they are also very useful for the survivors roaming the land. At their trading posts all the goods can be bought a survivor needs. Food, medicine, ammunition and other supplies.
These greedy traders wont give anything away for charity though. Everything has to be paid for with Roubles which can be obtained by looting or by selling looted items.
You should not expect to make a huge amount of money by selling trousers. The most looked after items in Chernarus are those which make surviving among bandits and flesh eating zombies easier. Firearms. Selling weapons will net a nice profit that can be reinvested into fresh supplies or -up to a certain limit- stored in the banking system at the trader outposts.
If selling weapons is not your style of playing on YourZ you can also choose one of the other ways to make money. From what other survivors have told us pelts and other animal products seem to go for quite a high selling price.