Aliexpress
Click here… to search for Xiaomi ROIDMI XCQCMS01RM Brush Head on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (40.27 USD): AM15prime
Coupon (41.69 USD): b71c67
Coupon (41.69 USD): BgAuMotor
(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)
Old coupons (from the oldest to the newest): 502C6B, e2bcea
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi ROIDMI XCQCMS01RM Brush Head? There we go.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).