If you're new to the sport you may be frustrated by the cost of flies and the number that you loose to trees and snags as well as breaking off a trip. Eventually you will end up with several fly boxes filled with 200 ~ 400 flies. At $1.95 each retail that's quite a bit of money. Some think that they can actually save money by tying there own but soon find that they have thousands of dollars inversed in materials.
On a good day I've actually come off the river with more flies that I started out with. Sometimes when I get hung up on an overhanging branch I'll carefully check the leaves and have on several occasions pulled more than my own fly from branch.
Now I'm not going to tell you to stop shopping at local fly shops, I will stop in a buy a few of a special pattern that I don't have the time or inclination to tie. But I wouldn't mail order from them, with added shipping cost you'll be paying a small fortune on flies. But when in the neighborhood, do stop in ask about the current conditions and hatches, check out a new rod and buy a 1/2 dozen of the flies they recommend. If you want to do some serious fly box stocking you might want to try some of the internet fly shops that offer decent quality at a very reasonable price.
Here is the short list, feel free to add your favorite site and experiences with them.
#1 Blue Fly Cafe Fast Reasonable A+ service Also stock some basic accessories like loon products. I've ordered from them many times and have never had any issues. $0.74 ea. $7.68 doz.#2
Caylor Custom Flies Local NC home grown tyer A little more expensive but $1.00 ea, $10.00 doz.
#3
Hooked on Flies How about the Fall Special 100 flies for $25 !!!!! or $0.59 ea.
Here is a thread with more info...
http://www.brfff.com/forum/index.php/topic,645.0.html