Knowles SPU0410LR5H-QB on pcb
€5.00
One small Knowles SPU0410LR5H-QB microphone element on a small 0.6mm thick FR4 PCB with two 1uF capacitors.
Choose for rectangular or even smaller 7mm round model. The rectangular mode can be used with 2.54mm pinheader, the round one only accepts thin wire, it can fit in a 3.5mm jackplug.