For dries, good quality hackle can certainly help keep things on top. You don't need top-of-the-line stuff - with all the advances they've made in breeding birds specifically for tying (and not for table) stuff labeled tyers grade would have been the Holy Grail back in the 70's when I started. Most of my stock would be considered #3 grade and it works just fine (I do have a 1/2 neck Whiting silver label in brown that I pull out once in a while just to see how the upper crust live).

Stuff like ungulate hair, you can get by with just about anything - the more expensive stuff (think Blue Ribbon Flies, and actually their product isn't all that much more) will definitely make for a prettier fly, but even hair with broken tips and a definite curve to it will float.

For dubbing I use a lot of rabbit and it's pretty cheap; except for some of the synths used in salmon/steelhead flies, most of the other furs are inexpensive, as we'll.

Most online flyshops prices will run about the same pricewise; maybe a bargain or two out there (I do like Blue Quill Angler - good inventory and free shipping on orders over $15). Knock on wood, I've had very good luck buying materials on E-Bay at decent prices. Go to the nearest craft store and you'll find plenty of useful items - ostrich, peacock, foam, etc.

Regards,
Scott