Ok, to make some money for all of you free players that are level 5 or higher with about 300 hp. First make room in your inventory and buy some food, like 10 withered apple. Then go to the entrance to the goblin cave but do not go in and kill the monsters. Instead go in the goblin cave and come out and kill the monsters outside of the goblin caves. Doing this repeatedly, my character gained 250 gold in less than 30 minutes. Also, if you are a level between 15 and 20 please do not horde this spot. This is for level 5-15 people.
When you're done gathering gold (Also known as "Farming"), press the Warp Map icon on lower right part of your screen and select "Return to Inn", you'll go back to the inn instantly. Once you reach the inn, you can sell all of your loot. You get the point if you buy no food you can make a huge profit.
Sometimes goblins will drop valuable items such as jewelry or equipments, that items can be sold for a high price at the NPC.