Most exercises listed in this book (Intelligent Carb) can be performed with body weight or with very inexpensive equipment. A pull-up bar is one basic piece of equipment that is needed. As mentioned in the book, a very inexpensive custom pull-up bar can be made by purchasing pipe and some pipe floor flange fittings from a local hardware store. Be sure to hang it with good, long screws into studs. Pull up bars can also be purchased:
https://www.walmart.com/ip/Perfect-Fitness-Multi-Gym-Original/19792716?wl13=1505&selectedSellerId=0
https://www.lowes.com/pd/Pure-Fitness-Pure-Fitness-Multi-Purpose-Doorway-Pull-Up-Bar/1003243170
Resistance bands can be purchased at many different locations. What you are primarily looking for in a resistance band set is something with handles that you can grasp and bands with different resistances that you can attach to the handles to be used for different exercises, and to progress as you get stronger and can lift more weights.
Other types of bands can be useful as well, especially when used to provide additional resistance on squats or to assist with pull-ups.