Where can I find good Fly fishing vests and outerwear?

Check out cabela's or gander mountain.
References :

Cabela's will have a decent amount of fly-fishing vests and outerwear. But do a quick "Google" search on "fly-fishing shop" or "fly-fishing vests" and you will find a few sites that may even specialize in what you are wanting.
References :

I like to use a local shop as much as possible. It is often more expensive but it keeps the $ in the local community instead of sending it to corporate H.Q. in N.Y. City.
References :

Go through the site
http://www.globalsportsinc.ca/fly-fishing-c-233.html?osCsid=fc4ba5739f231407e805128ce55688f2 for good fly fishing vests and outerwear. Different collections of fly fishing vests and outerwear are there. You can get it at low cost.
References :
http://www.globalsportsinc.ca/fly-fishing-c-233.html?osCsid=fc4ba5739f231407e805128ce55688f2