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Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. Well, there is one coupon available right now.
Link: Banggood product page
Coupon (136.40 USD): BANGGOODSD
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart 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): BGXIN186, BgcLuBofErtA10, BGAFF10OFF, BGHR186, BGCuponation10, 7bcdf9, BGHONEY2110
(there’s a little possibility that old coupon will work)
Price history and price alert
Check out price history chart (for all/most countries) for Petkit Air Purifier.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).