Aliexpress
Click here… to search for Xiaomi KONKE Zigbee 3.0 Human Body Sensor on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (10.79 USD): BGHONEY2110
Coupon (10.99 USD): 13f142
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): BG9NY, BGAQ20, BGHOMEAPP, bGhOnEy10, BGSM15, BGSS10%SW, bgshOOp10, BGSAMRTH, BGELIG0920, BgcLuBofErtA10, BGAFF10OFF, BGCuponation10
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi KONKE Zigbee 3.0 Human Body Sensor? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).