Aliexpress
Click here… to search for Brush Cover for Xiaomi Vacuum on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. One coupon is available. Cool!
Link: Banggood product page
Coupon (11.39 USD): BG00c906
(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): PICODICOM, Accessories, aff7off, bgssaff9, BGaDmITAd, 13f142, BGBFAFF2019, BGCITYADS2019, 2020CNY, BGVDay10%off, BGHOMEAPP, bGhOnEy10, BGTT10, BGSS10%SW, bgshOOp10, BGHome15%, BGHOMEAPP13, BGHOMEA13, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BANGGOODSD, 00c906
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for Brush Cover for Xiaomi Vacuum is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).