I believe in China they call these spy earpieces (间谍耳机), but since spying in China is illegal, and since my purpose is not to spy, I shall just include this term for ease of answering.

Preferably in Shanghai or Ningbo.

Specifications exactly as in http://www.gsm-earpiece.com/covert_liste…

Pricing on these sites are just overwhelming.
Reply to Johnny:

Nano is the common name given to it.
Technically it would be micro.
But the "nano" series is a tad smaller than the micro series.

I've already been through the googling process, and now I'm here. Prices you find online are astronomical.

Since I'm travelling to China soon, and knowing that China is the hub of electronics, I pose my question here.