Items rotate in and out of availability. Just because an item is gone now, doesn’t mean it is gone forever! Some items return seasonally, while others don't come back to stores. If an item is marked as "Rare," it's likely that exact item and color variation won't be returning to stores. Occasionally a new color variant of that item may become available for purchase.
Unfortunately, we are unable to share information about future updates. In the meantime, the best way to get an item that is no longer in stores is through safe trading with other players or purchasing from another player's My Shop.
Other articles about trading: