Just check coupons out (with price alert and history). Let’s see what best price is ATM.
1x USB Cable, 2x Brush Head, 1x English Manual, 1x Charging Holder, Package Contents: 1x Smart Toothbrush with Brush Head
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):
Price history and price alert
Do you need price history chart (for all/most countries) for Oclean X Sonic Toothbrush With 3 Brush Heads? There we go.
Price records source(s): Gearbest
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)).