Hard to determine which supplier is the best. It comes down to prices and service. At anytime, one certain supplier might have some items that are less costly, but also might have items that are priced higher than another supplier. You have to leapfrog the catalogues, online or hard copy.
These days, shipping costs have to be factored in. I used to buy a lot of gear from Cabela's, and was always satisfied. However, I see that their shipping cost has been considerably increased. It will be a cold day in hell before I will pay $8.00 S/H for a $3.00 item.
Krueger Archery Supplies
http://www.texasarchery.org/BidnessAds/K/PL.HTM
F / S Discount Archery (Over the years, I have purchased many items from F/S and was always pleased.)
http://www.fsdiscountarchery.com/index.html
BCY String
http://www.bcyfibers.com/technical_sheets/
TrueFlight Feathers
http://www.trueflightfeathers.com/
Fiber Optic Material
http://www.ccl-light.com/docs/fiber/fibercable.html