Input Voltage: DC 5V, Net Weight: 136g, Brand: Usmile, Battery Capacity: 2500mAh, Modes: White/Clean/Soft, Handle Material: PA/ASA, Noise Standard: 60dB, Vibration Frequency: 38000/min, Waterproof: IPX7, Charging: Type-C 5H, Size: 30.5*30.5*252mm, Working Time: 180 Days, , Model: Y1S.
Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. We have found one coupon for this product!
Link: Banggood product page
1. ($64.39): BGCAPITALOS8
coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BG421252, BG4ee866, BG641f34, BGUSEU02, BGHOM035, BG8ReviTrage, Cuponation9, BGc1dd31, BGf9f048, BG75597c, BG5e295c, BGde7078, BGbdfbb1, BGee7cef, BG589b2e, JanBGCoupon8, BGSaleFeb8, BGAUGUST8
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for Usmile Y1S Sonic Toothbrush is here. The lowest price was: $29.62.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).