Hi, thank you!! There's so many great resources for building your own quad from scratch (ex https://www.youtube.com/watch?v=S9dvDU5RmQU&t=476s). I honestly wouldn't recommend an octo unless you have a reason for it (like wanting more fault tolerance, etc) solely because it's twice as expensive for the motors. I got all my parts from GetFPV and Amazon. At the very bare level, all you need is a FC, ESC, frame, props, motors, receiver, and battery (plus controller, and goggles/camera if you want it to be FPV)