Aliexpress
Here are coupons that you can use.
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – Digoo DG-YS33 Sonic Toothbrush White (-3 USD)
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (16.35 USD): AFfbG10
(CouponsFromChina.com tip: you should apply the coupon 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): YS310, TB159, 3776eb, 0404digoo, e2bcea, vipupgrade8, TTxBG10, bgssaff9, 502C6B
(I don’t think these’re gonna work, but you can try ’em out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – Digoo DG-YS33 Sonic Toothbrush White (-3 USD)
Price history and price alert
Here is price history (for all/most countries) for Digoo DG-YS33 Sonic Toothbrush Black.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).