Now a days there are quite a few Flyshops that have great items offered and catalogs and websites.
Here In the Lehigh Valley there are no flyshops anymore.In the Poconos ,IMHO the Best 3 shops were Silver Springs Outfitters in Kunkletown{Brian Tartar},AA Outfitters White Haven { Bob Sentiwany},Evening Hatch {Ken Shiffert,Tony},And yes in Stroudsburg thers Windsor flyshop,and Dunklebergers.Silver Springs is gone Brian retired,and now i would Rate Evening Hatch As the best in the Poconos{be it the western Poconos}.
In North Central Pa i can only comment on one that i used to buy a hellish amount an that was Fred Reese's Trout Shop in Jersey Shore also when Bob Pearson took over and the Shop was in Avis for a lil while.Fred Did his own Materials was spot on for ccolors when wet be it dubbing or feathers.I miss this shop. I have never been to Kettle Creek Fly Shop,Or Slate Run,or Hille's I can't comment on any of them till i do however I would like to check out Great Meadows Flyshop if Sandfly doesn't throw in the towel ,seems like a great guy here in the forum.
In Central Pa IMHO Flyfishers Paradise is my first choice,TCO is ok,never been in the Feathered hook in Coburn but next trip to Penn's if hes open ill stop in.
In South Central Pa the shop i used to go to is done that was Cold Spring Anglers in Carlisle, had a good catalog and the shop was good too.Never been to the Yellow Breeches, will stop there if i get over that way.Bob Clousers in Middletown is a great shop too i don't know if hes still open or just online but that shop was a tyers dream,i have been there several times.Hook prices were great and also had many materials.
Abroad i'd say the following are Shops can be trusted, i have ordered from their catalogs : Flyshop{Redding,Ca},Bob Marriot's{Fullerton,Ca},Leland Flyfishing Outfitters {SanFrancisco,Ca},Redshed { for all things Spey,Peck ,Idaho}Blue Ribbon Flies {West Yellowstone ,Montana}Trout Hunter{formerly House Of Harrop,Henry's Fork Of the Snake River,Last Chance, Idaho}Madison River Flyfishing Company {Ennis,Montana}