Here are places to buy stuff online:
online tools to find parts cheap
Octopart: cross-vendor search engine for electronic components – good, but requires some sophistication to use it.
A little more expensive, but usually have good pictures and support so you actually know what you’re buying.
sparkfun: Good range, helpful images and tutorials
adafruit industries : Great tutorials and a good range of parts and DIY electronic kits
RobotShop: good range of parts, micro controllers, sensors and actuators parts, including muscle wire.
Usually a little harder to find exactly what you want but cheap.
mouser: A very large range of components and some sensors and actuators. It’s very easy to get lost looking for parts here so it’s best to know exactly what you need before looking.
digikey.com and jameco.com : General electronics parts retailers
Talk to us if you are curious about getting Bluetooth radio modules, RFID tools, or other hardware.