Sparkfun Electronics – Specializes in hobbyist electronic components, tools, and kits. The website features a project blog, buying guides, and tutorials from soldering to using a breadboard. Ask for educator discounts.
Adafruit – Unique and Fun DIY Electronics and Kits. Check the Young Engineers section for selections that are whimsical and fun. Ask for educator discounts.
Maker Shed – Make Magazine online store. Kits, maker hobby items, and books.
Robotshop – All your robot needs in one place. Robots for home, school, and professional use, plus drones, wearable technology, kits, toys, parts, and apps.
Digikey – Extensive collection of electronic components. If you can’t find it here, it might not exist!