Audio & Microphone
No one notices your microphone, until you have bad quality audio.
They will watch your video even if you're in the dark, but people will not watch it if the audio is bad.
You'll only need one of the three options below.
What you should get
Podcast Mic + iPhone Adapter
Lapel Mic + iPhone Adapter (if you plan on interviewing other people or being mobile)
The minimum you'll need to have
Your cell phone microphone, if you're in a very quiet room