Here is a thought about what to do with all the stuff people sell to npc that could be useful to many people but not having the will or space or whatever reason they sell everything to npc. There could be a sort of "Flea market" where everything that is sold to npc in certain town is gathered to some other vendor who sell it at a discount and considering how much of the item is avalaible and how high is the demand for said item. Would be another alternative to the market ward and also help player gather what they need if they are willing to spend gil instead of time gathering.
Those are some tought to help player who wich to spend gil instead of time, because gil is easy to make in this game.
Thank you for your time reading this.