Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (34.53 USD): Cuponation9
(CouponsFromChina.com tip: you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
There were country-specific coupon codes published on Couponsfromchina social channels and price alerts. Coupon price may vary by country, because there’re different VAT rates, shipping cost etc. There is a chance that some latest coupons are still working:
Old coupons (from the oldest to the newest): BGbe2133, 8wEbgaInS5, hoNEYbGdeAlS, BG6d2f05
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for 120cm Adjustable Air Conditioner Window Kit Plate.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).