You can create price alert here, copy coupons and view price history. Do you want to know what the best price is?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Waterproof Level: IPX7, Main Power: 2.5W, Product Name: Ocean Air 2 Smart Sonic Electric Toothbrush, 2. 5 hours full charge for 40 days of battery life, Mode: Gentle (Default Mode), Brush Head: Magnetic brushless moto, Input: 5V / 0.5A, Clean, Motor: Magnetic brushless motor, Weight: 95g (Including toothbrush body and head), Charging Specification: USB Magnetic Charging, Size: 235x 24mm
Banggood
Banggood warehouse is located in China. There is one great coupon!
Link: Banggood product page
1. ($45.04): BG75597c
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BgcLuBofErtA10, BGOC279, BGAIR229, BGAIR2499, BGAR3677, BGAFF10OFF, BGCuponation10, BG22371, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BGHB218, BGXPAP293, 2203ActiesNL, BGHUMA051, BGHECARE1, BG5a9339, BG4ee866, BGHOM020, BGHUXC023, BGcd7367, Cuponation9, BG36a004, 9OFFSUMMER, BG153121, BG989d84, BGf4eef2, BG3fc3f7, BG606174, BGcc265b
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Oclean Air 2 Sonic Toothbrush is here.
Price records source(s): Gearbest, 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)).