Aliexpress
Here are coupons that you can use.
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – Xiaomi Roborock S6 Robot Vacuum Cleaner Black [EU] (-3 USD)
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (539.99 USD): BG10OFFAFF
Coupon (590.99 USD): 7bcdf9
(CouponsFromChina.com tip: put item in your cart and apply coupon code there 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): BGHKBS6, BGAFF7OFF, bgshOOp10, BGHOMEAPP12, BGHOMEAPP13, BGHKRCKS6, BGHOMEA13, BGCZRBLS6, BGS6nero, BGHKRBFS6, BGCZBLARS6, BGHU0193, BGCZRBKS6, BGCZBCKRCS6, BGCZBGHYTS6, BGCZDRBS6, BGCZRTUBS6, BGCZPRRBLS6, BGCZBSGRBS6, BGCZREDSPS6, BGCZSCPBS6, BGCZERGS6, BGCZREBCS6, BGitMiFanS6, BGCZRSDS6, BG10OFFAFF1, BANGGOODSD, 6GSGIT, 00c906
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – Xiaomi Roborock S6 Robot Vacuum Cleaner Black [EU] (-3 USD)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Roborock S6 Robot Vacuum Cleaner Black.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).