Aliexpress
Click here… to search for Xiaomi ROIDMI M8 Vacuum Cleaner on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
Coupon (197.36 USD): BGAFF10OFF
(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): e2bcea, 502C6B, BgAuMotor, b71c67, AM15prime, BGCS20, BGdoublezx, BGAutos, bGhOnEy10, BGCARELEC
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi ROIDMI M8 Vacuum Cleaner.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).