We discussed item trading between players in the last chapter. We are going to discuss trading items with NPC now. The difference in trading between NPC and trading between users is that the former creates a new item and sells it to the player and the latter just passes an item from one player to another. The item creation process means the total amount of the items inside the virtual world increases, and it may lead to a virtual economy problem such as inflation. Therefore, some virtual worlds will set a limit to some rare items that even the NPC will not always sell. Instead, they will mark it as no stock until the amount of the items is below the upper limit.
Not every NPC sells the same items. Some NPCs may sell weapons and some may sell healing tools. It is one of the task for players to find out where the specific NPC appears and sells items. And also it is a challenge to find an NPC who sell rare items but appears only at certain times in a place...