Meteorites are an alchemy ingredient. They are one of the rarest ingredients in the game and used in only one formula.
No merchant directly sells Meteorites. However, it is possible to buy them, in a roundabout way.
In Crustacia, a Mad Monk will sell the player an Amulet of Annihilation for 10,000 Jewels. When the player purchases the Amulet, the Monk also gives them a Charm, depending on which Charms the player already has. If the player owns the Chocobo Egg, Wizard's Coin, and Magic Gourd, the Monk gives them 3 Meteorites. The player can then get rid of their Amulet in some manner so the Monk will reappear, and they can buy another Amulet with another 3 Meteorites.
However, keep in mind that there is no need to purchase more Meteorites than you have Dry Ice, which is not sold in any way.
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