For more background information about the shakuhachi, its history, making, different schools and teachers, etc, here are some links:
The International Shakuhachi Society: www.komuso.com
The European Shakuhachi Society: www.shakuhachisociety.eu
Shakuhachi Resources: www.shakuhachi.wikidot.com
Komuso Blog: Komuso Khronicles
Shakuhachi shops
Shakuhachi Store and Workshop: Tai Hei Shakuhachi
New Bamboo and Second Hands flutes: Mejiro Japan
A very good flute to start with: Shakuhachi Yuu
I personally love the shakuhachi Yuu to play in nature.
I made a playlist of my videos called Seiyu and the YUU