Aliexpress
Click here… to search for Xiaomi Aqara Smart Air Conditioning Controller P3 on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (50.14 USD): BGSHOM15
Coupon (53.09 USD): BGHONEY2110
(CouponsFromChina.com tip: put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGAQP3, BGSMOFF, bgshOOp10, BGSAMRTH, 7d18f7, BgcLuBofErtA10, BGAFF10OFF, BG15SH12, BGSTHO15
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Xiaomi Aqara Smart Air Conditioning Controller P3 is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).