If you have not tried Saddle Hackle, here is a great way to get in the game.  A saddle hackle is a fairly long feather of consistent fiber length.  Saddles typically have a smaller range of sizes (12 – 16 or 16 -18) but each feather will tie several flies, verses a Rooster Neck which provides a broad range of sizes but only 1 fly per feather.  I try to use Whiting hackle – both Saddles and Necks as much as I can for my dry flies – there are a few colors where you have to get playful. The quality of the Whiting material is consistently superior – the quill is soft & straight and  the fibers are stiff, dense and web-free.  These 100 packs are pre-sorted by hook size and cost around $10.  A nice way to try their saddle hackle and get a feel for sizing without the financial investment of a full saddle.