Aliexpress
Click here… to search for Original 2x Filter for Xiaomi Vacuum on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is no active coupon in my database right now (for Banggood).
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): PICODICOM, Accessories, aff7off, BGALPARTS, BGaDmITAd, bgchinafest, BGBFAFF2019, BGCITYADS2019, 2020CNY, BGVDay10%off, BGHOMEAPP, BGTT10, bGhOnEy10, BGAFF7OFF, BGSS10%SW, BGHome15%, BGHOMEAPP13, BGHOMEA13, BG11SHOP, BG10OFFAFF, BGwhielabel, 13f142, BG10OFFAFF1, BANGGOODSD, 00c906, BG00c906, ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, 2203ActiesNL, BG1efeb0, MVC8SPRING
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Original 2x Filter for Xiaomi Vacuum is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).