You can create price alert here, copy coupons and view price history. What is the best price?
Up to 42000rpm, Brushless Motor: , Up to 220gf.cm
Aliexpress
There’re some similar (or not) items on Aliexpress
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. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
1. ($65.31): BGCAPITALOS8
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): BG8466, BG8461, BGCuponation10, 13f142, BG10OFFAFF, BG75597c, BG3cb289, BG589b2e, JanBGCoupon8, BGSaleFeb8, BGAUGUST8
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Oclean X Pro Sonic Toothbrush with Additional Head is here.
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)).