Once you defeat the Elite 4 for the first time during the story, you can travel the eastern side of Unova. From Nimbasa City, go east to begin your journey. You will end up on Marvelous Bridge. Once there, notice that you will occasionally hear a "wing-flap" sound, and a small dark area (similar to those seen in lakes and in caves) will appear in a random location on the bridge. There will be a 50% chance that when you step on the dark spot, it will either be a "Wing" or a Swanna, the White Bird Pokemon. These "Wings" include the Health Wing, Muscle Wing, Resist Wing, Genius Wing, Clever Wing, Swift Wing, and Pretty Wing. These all give effects similar to those of the Vitamins (Protien, Iron, Calcium, Zinc, etc.) but can be sold for 1,500 PokeDollars. They are very easy to obtain. Keep finding these "Wings" and sell them in large quantities.