Well, some of the best places to buy flies, are the local fly shops to where you will be fishing. Often they will have a selection that is good for that area. With that being said, there are abundant online fly shops that will sell flies for a cheap price. Quality varies with them. Some that come to mind are
www.bigyflyco.com ,
www.discountflies.com or
www.theflyshack.com and of course, Ebay.
I have made my own screen to sieve out the water bugs by attaching a fine mesh plastic screen between two dowel rods, cut to size. I keep it rolled up in my pack, and when I want to see what’s in the water, I stick it in moving water down to the bottom and kick a couple rocks in front of it to stir up the critters, then look to see what’s moving on the screen.
I don’t do much bass fishing, but if you do get into fly-fishing, you will start to hit the streams, and if you do so, my recommendation would be:
Nymphs / wet / streamers: flash back pheasant tail, black AP, micro mays, brown rubber legs, callibaetis, and wooley and crystal buggers.
Dries: parachute Adams, parachute adams, elk hair cadis, stimulators, pale morning duns and did I say parachute adams?
Terrestrials: ants, ants grasshoppers, and more ants.
As for bass flies… whatever pisses them off.
just my .02...