Feel free to add any web locations to this list as it should be "growing" all the time! I'm sure a lot of you know some great places to purchase materials that some of us might not know about.
If you are interested in learning how to build rods, I recommend YouTube. Specifically "GetBit Outdoors" with Captain Kevin Brotz. He has a great selection of short videos that take you through every step of the rod building process.
Here is a list of locations I use to purchase materials, blanks, and componants: