There was a moogle that sold them in each of the major cities. One in Apkallu Falls in Old Gridania, one in upper Lisma Lominsa and the other near the heart of Ul'dah. They were purchasable for 1 gil (which, I suspect, the new earrings will be as well). They also announced when the moogle was going away so that, if you wanted them, you better hurry and purchase them.

Personally, I wish they were also bringing back the bomb earrings. I loved those bomb earrings.