Aliexpress
Click here… to search for Xiaomi SWDK Q6 Automatic Aromatherapy Sprayer 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 (24.16 USD): PICODICOM
Coupon (24.16 USD): aff7off
(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): bgssaff9
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for Xiaomi SWDK Q6 Automatic Aromatherapy Sprayer is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).