This is a comprehensive parts list for the course. There is a list of parts by project as well as individual listing of parts. Whenever possible, I try to provide a few purchase options for a part from different online retailers.
Buying an Arduino kit is a great idea since a lot of the parts we are using come bundled in a kit. A kit can possibly help you to complete 80 - 85% of this course. I have placed links to a few kits in the parts list.
A kit is also a good investment if you are serious about learning electronics as it comes with a good base of electrical components to start with.
If you have an online electronics retailer that you prefer especially based on your location, please feel free to use them as well.
If any of the links are broken, please let me know and I will get them corrected. I try to keep this list as up to date as possible.