Noise: 65dB, Quick Charging Time: 16 hours, Standby: About 25 days, Waterproof Rating: IPX7, Rated Voltage: 3.7V, Charging Port: Type-C Charging Cable, Power: 2W, Color: Black & White.
Go down and check coupons out. Remember to check price history if it is available. You probably want to know what is the best price?
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 code price check (UTC time):
Banggood
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it?
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGMAR1906, BGMAR1901, BG10OFFAFF, BGwhielabel, BGPL112, BGXPDC20, BGSSX3U1, BGGRE293, BGISXP285, BG10OFFAFF1, BGDQXP31, BGSEXP136, BGSEXP271, BGNDH08, BGDU1125, BGHealth06, BGNOXP153, BGHWTB1
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for SOOCAS X3U Sonic Toothbrush is here. The lowest price was: $22.99.
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)).