Where to get Shark Fin
Unless you want to pray to the RNG gods by running the Labyrinth and hoping this material will drop, there are two places you can reliably go to buy Shark Fin. The first is the recycling center on Aloha Beach. This woman will exchange any trash you collect from the beach for points you can spend on various items in her stock. One such item is, of course, the Shark Fin. This is one of the most expensive items she has, however, so it will take a lot of trash collecting to earn enough points. You must also consider that she only has three, so you can’t spend all day gathering bottles and cans to stock up.
The other option has unlimited Shark Fins to buy but is more dangerous. Robo Michio outside the Labyrinth also sells this crafting item in exchange for the Robo Disks you collect while running through the dungeons. Again, this is an expensive buy and will cost 15,000 disks for each one. However, since you do have a chance of finding one in the Labyrinth itself, it isn’t a bad way to hedge your bets if you’ve exhausted the first method.