JD558
Part of the JD New Year Sale
$60 OFF Orders $300+, $40 OFF Orders $150+, $20 OFF Orders $50+, $8 OFF Orders $10+
Cheapest price I've seen for piston III earphones, highly recommended.
A few other good deals from the sale with the same code:
Xiaomi also lowered the price for these to 69 CNY (US$10.70) and the seller is JD themselves, so I guess they're most likely genuine.