What will be most balanced way to deal with the loot (armor, weapons) from dead enemies?

After a successful fight party constantly checks enemies bodies for any kind of loot – their weapons and armor too with the intent to sell in the city. As reselling enemies equipment is mechanic encountered in most cRPG games I think it should be allowed. However, as the party is a low level I’m afraid that it has a chance to destabilize game, by making them rich too fast.

I’m looking for a fair system or a method of dealing with looting weapons, armor and other equipment, which works in your games.