Arduino
Tons of resources for getting started with Arduino and troubleshooting problems along the way.

Arduino.cc
Arduino Forum
Element 14- Arduino Tutorials
mjlorton Arduino tutorial on YouTube
Spark Fun Arduino Forum
Arduino Reddit Forum
AdaFruit Forum

Supplies
Here are some great websites for buying supplies, please let me know if you have more suggestions.
*Note* most of theses stores ship internationally but it may cost more.

North America:
Spark Fun
Ada Fruit
Robot shop
Asia:
Seeed Studio
Ali Express
Europe:
Arduino Store
Robot Shop
Australia:
Freetronics

Wearables/DIY
Here are some great sites for further wearable/DIY inspiration !

Make Magazine
Hack A Day
Fashioning Tech
AdaFruit Wearable Blog
Kobakant DIY Wearable Blog
Lily Pad, Arduino specifically for wearables
Soft Circuit Instructables, a collection edited by Laura Khalil
All About Circuits Arduino Projects