Contact 3Rivers Archery. I ordered a packet of dye. It is a small envelope, but there is enough to make 1 gallon. Heat the gallon of water to nearly a boil, add the dye, stir. Your done. Put your feathers in the mixture for about 1 minute. Remove and let dry. Works good for me. They have many colors to chose from. When you are done, pour into a gallon jug to store. Don't let it freeze and break.
Problem I have seen with the koolaid mix, is the dye comes off on your bow and hands in time and the colors are not as sharp.
Be sure to use an emamel pan for this. I found an old roaster pan. It will stain nearly everything!
Just my opinion