Fennec wrote:I'm looking for a good gaming headset MIC for audio commentary.
Either live-in game commentary or for recording voice-over work in Audacity.
I've heard the Astro A40's are good.
Has anyone used them or have any other suggestions?
The Astro A40's are definitely a great pair of gaming headset.
However if you already own a headphone then it isn't worth going for a completely new headset.
for 3/4th the price of Astro A40 you can get a great performing condenser mic like the Samson Meteor http://www.amazon.com/Samson-Meteor-Studio-Microphone-Chrome/dp/B004MF39YS/
However if you want to go a little more cheap then you can check this guide about good microphone for http://theroundingsound.com/best-microphone-for-gaming/.
I hope that will able to help you a little more.