The 100 packs from Whiting Farms are on of the most popular ways to get into tying dry flies. You're able to get identical, perfectly graded feathers. Some reaching lengths over 12". In one pack you will be able to tie 100 flies! 
This is a great way to see if you enjoy tying dry flies before investing into whole capes and saddles, or for sizes/colors you may not need a lot of!