Massdrop offers the AntLion ModMic 4.0 in Standard or Omnidirectional for $34.99 plus $5 for shipping. That's $8 off list and the lowest total price we could find. This microphone attaches to headsets and features 100Hz to 10kHz frequency response and 2.2 KOhms impedance. Deal ends February 28.
Of note, both styles are also available as muted versions for $5 more, and base clasps are available for an additional $5.