Ears of millioncorn can be bought at a shop, but it depends on who's controlling the area.
With my fame, I lost 18 gil everytime I did the quest, but it was well worth the money. After repeating it 40 times, it opened 2 new quests in Selbina, one where you hand in particular rolanberry, and another where you have to rescue 2 ppl from Badeaux.