These Telinga EM23 are about $520/pair. The capsules are the Primo EM23 (there is also EM21, a cardioid) and they are about $55 from them. I got a schematic from Klas Strandberg of Telinga. They seems to be intended for lower level work, like nature recordings or acoustic imstruments. Their noise level is low compared to a standard Nakamichi with the same capsules. The balancing output transformer of the Nakamichis drop their output level quite a bit and it put some demands on the mic preamp. Removing the transformer gives a lower noise floor, 5-8dB seems to be common. EM23 is a bit rolled-off above 10 kHz but as it is an omni capsule, bass is extended even at a distant pickup. I have several schematics that seems to work with EM23/EM21.
Roger