check out fishandsave.com I know next to nothing about flies, but they advertise Hank Robert's flies and they have them on sale. Pretty large selection. I ordered some saltwater deceivers from them for teasers during surf fishing. S&H is reasonable also.
I also have bought flies from a guy on EBAY, his username is riplipsfishing in the past. He hand ties them himself and his prices were very reasonable. Maybe not the same selection, but he is also open to emails where you request specific styles/colors, etc. Good guy to deal with. Here's a link-
http://sporting-goods.shop.ebay.com/i.html?_nkw=fly&_sacat=382&_ssn=riplipsfishing&_odkw=&_osacat=382&bkBtn=&_trksid=p3286.m270.l1313