Just check coupons out (with price alert and history). Let’s see what best price is ATM.
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):
With 32 intensity levels, 000 frequency, Up to 40 days battery life, 42, 2 hours fast charging
Banggood
Banggood warehouse is located in Hong Kong. Well, there is one coupon available right now.
Link: Banggood product page
1. ($62.55): BGCAPITALOS8
this code has to be applied in your cart 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): BGXPRO7, BgcLuBofErtA10, BGOCXP1, BGOC3575, BGOCX32, BGBFC059, BGYXB399, BGOC1209, BGOC1212, BGOCP399, 7d18f7, BGAFF10OFF, BG14876PO, BGIS14876, BGHU0296, BG19561, BG14876, BGLA4999, BGDC876, BGRSPRING27, BG22371, BGWTR76, BGLC876, BGOC3999, BGMAIL05, BGMAY3799, BG10OFFAFF, BGMAY047, BGMAY082, BGwhielabel, BGjune08, BGISRAEL02, BGGM0530, BGCN0526, BGXPROIT, BGMAY073, BGjune25, BGjuly11, BGjunePT, BGxpro18, BGjuly10, BGjuly64, BGjuly49, BGjuly20, BGsale710, BGISRAEL05, BGjuly08, BGjuly60, BGjuly77, BGdeal0708, BGesp0708, BGprtul708, BGxpro99, BGeu7008, BGnd314c, BGad610f, 13f142, OCLEAN77, OCLEAN99, Oclean33, BGc432df, OCLEAN44, OCLEAN88, OCLEAN456, OCLEAN123, BG10OFFAFF1, OCLEAN882, XIAOMI77, Portug55, BGSV523F, OCLEAN147, BGHU0889, BG0a0495, BG923e7d, BGf4a178, BGb74646, BG68bbd5, BG4c6927, BG458758, BGaae394, BG6da972, BG612553, BGe4f36d, BGde39ea, BG7c80d4, BG32bca8, BGef2381, BGb419e5, BG8f7beb, BG81e611, BG87d747, BG51fa5e, BG655d3d, BGcbcfd3, BG108426, BGc76cd0, BG98dc5a, BGe346ef, BGHealth06, BGf77f0a, BGDBU41, BG5af74c, BG435f70, BG17df4a, BGc8eac7, BGBFQ26, BGdcc0ca, BG726272, BG1972e8, BGca4c4c, BGac5338, BGf3b25a, BG06dac0, BGHU1455, BGHU1586, BGHealth10D, BGDJJA261, BGISJA193, BGHUCJ193, 2022ACTIESNL, BGHB218, BGHUMA12, BGAFFOC2, BGHECARE1, BG4ee866, BGHOM019, BGHUXC024, BGISOC622, BGGEHOJ622, BGOCMHO23, BG61908b, BGGOCMH23, BGee79b8, Cuponation9, BG7af74b, BG9559da, BG8746f4, BGff5d46, 9OFFSUMMER, BG876787, BG75597c, BG3fab51, BG381232, BG2c2f86, BGe825cb, BGf5685b, BG4cad73, BGc11499, BG309e0d, BG589b2e, BGSaleFeb8, BGAUGUST8
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Price history (for all/most countries) for Oclean X Pro 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)).