Aliexpress
Click here… to search for YMYM YC1 Sonic Calculus Tartar Remover on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. One coupon is available. Cool!
Link: Banggood product page
Coupon ($33.99): 13f142
(CouponsFromChina.com tip: this code has to be applied in your 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): BGCNYMYM1, bgshOOp10, BGSJHome23, BGHome15%, bGhOnEy10, BGHOMEA15%, BgcLuBofErtA10, BGXPDE11, BGAFF10OFF, BGBTJUR0, BG63208, BGCuponation10
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for YMYM YC1 Sonic Calculus Tartar Remover is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).