If you want only talking, the best investment is a lapel microphone called a Lavalier (many companies have a Lavalier model, including the German brand Ironclad mentioned). It's near unidirectional and pick very little ambient noise. It's plugged into the camera (or audio device, pros never use the camera to record the sound). There are wireless models, but good ones are probably too expensive for home use.

You can get a decent Lavalier for around 200-250 US$.

What you don't need is another omnidirectional or near omnidirectional microphone (which the type attached to home cameras usually is) unless you purpose is to record ambient sound. That picks up everything. If you buy one that the person hands instead of using the one on the camera, the sound will be better and you won't pick the sound of the camera (as the mic on the cam does), but you will still pick up a whole lot of ambient noise.

I can't really tell about headsets used by gamers for your purpose, all I know is that the pros consider those mics complete crap.