Important ordering information: There is no minimum order, but in order to provide parts for as many people as possible, there is a maximum order amount of $100. Orders that exceed that limit will be automatically refunded. Also, as of March 2011, international shipping is now available. Shipments to the United States, Canada, or Mexico are trackable and insured. Shipments to all other countries are not trackable, and are also not insured.
Transistors
KSP2222A NPN Transistor: Two for $0.25
This is the transistor used in the IR Multi-Board.
It's also a good general-purpose NPN transistor.