Headset - A headset can be a very useful device during a video conference or webinar. Headsets are the perfect solution to echoes or problems with your computer microphone.
Webcam - One of the greatest features of video conferencing is the video. It’s really incredible to chat face-to-face with someone on the other side of the world. To do so, you need a webcam. Most new computers come with a webcam. If this is true for you, you are good to go! If not, you can purchase a webcam. Some webcams even come with a built-in microphone, so you may not need a headset. Also, when you look for a webcam, make sure that it is compatible with your computer.
Microphone - Most modern laptops and desktops have microphones. However, if you are going to buy an external microphone, make sure you know what can plug into your computer. Most are compatible with USB microphones.
Below are BigMarker's recommendations for headsets, webcams, and microphones -
Microsoft LifeChat LX-6000 for Business (BigMarker uses this brand)
Logitech HD Pro Webcam C920, 1080p Widescreen Video Calling and Recording (BigMarker uses this webcam.)
For demo-ing something on a table: IPEVO Point 2 View USB Camera