I can vouch for Markcanby's fly collections he's obtained from EBay. I've seen them. Although I give him a hard time about not tying his own, you can fill a fly box in no time and only spend a fraction you would if you bought from a store.
Have you had a chance to check out the tackle shop by Walmart? It's in the big red metal building with the glove company. You can access it through Walmarts' parking lot. I haven't been in,but they might be able to help.