Here are links to some of the products that are used in this chapter. Please do your own due diligence on these products and the retailers that are identified:
The USB-to-serial UART TTL cable is used throughout this book, for debugging problems with the BeagleBone, for viewing and interacting with the console as the board is booting and finally it is used for programming a low-cost Arduino Pro (3.3V) module. There are several products available such as those on Amazon: There is an official TTL-232R-3V3 cable, and lower cost alternatives (that have not been tested) such as the GearMo 3.3V Header-like TTL-232R-3V3 cable.
It is also very useful to have a 2A 5V regulated power supply, especially if you are planning to connect the BeagleBone to a Wi-Fi adapter, USB webcam or LCD cape. It is always useful to have such a power supply for writing a new image to the eMMC. Here are a few such examples: 2A 5V power supplies on Amazon.com.