Electret Microphone Amplifier - MAX9814 with Auto Gain Control : ID 1713 : $7.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Electret Microphone - 20Hz-20KHz Omnidirectional : ID 1064 : $1.50 : Adafruit Industries, Unique & fun DIY electronics and kits
Electret Condenser vs True Condenser Microphones
Amazon.com: uxcell 8Pcs Cylindrical Electret Condenser Microphone Pickup 85dB Through Hole Mini Electret Condenser Mic with 2 Pins 10x7mm for PCB : Musical Instruments
Amazon.com: uxcell 10Pcs 6mm x 3.5mm 2 Wire Cable MIC Electret Condenser Stereo Microphone High Sensitivity 3.5mm Electret Microphone : Musical Instruments
Electret Microphone - Pacific Antenna
Amazon.com: Adafruit Electret Microphone Amplifier - MAX4466 with Adjustable Gain [ADA1063] : Electronics