Check out prices online or at your local fishing shop and compare - you may be able to save money and get better components if you make your own. Get a vise, which helps the fly fisher do his or her tying. Vises come in two styles, pedestal and clamp, with the pedestal allowing more flexibility because it's free-standing. Spend a little extra to get fine-tipped, sharp scissors that will allow your fly tier to clip in small places or when using fine materials. Include a bobbin, which holds the spool of thread as the fly is tied.
Bobbins come in different lengths and widths.
Get a pair of hackle pliers, which are used to wrap the end of the feather around the hook. See if you can afford ones with a rubber jaw that won't cut the feather as readily as the kinds with the metal-serrated jaw. Include a basic fly-tying book with pictures that will give your fly fisher some ideas about how to get started tying flies. Use your imagination and come up with an alternative to wrapping for presenting your gift. However, a toothpick or pin can serve the same purpose more inexpensively.