Aliexpress
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 USD
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!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): AFfbG10, vipupgrade8, BGKONPL2, BGHEADSPL, 502C6B, BGVDay10%off, BGOcleanBH, BGAFF10OFF, bGhOnEy10, BGbeauty001, bgshOOp10, BGHB20, BgoFErTaSchInA10, BGSD58965, BgcLuBofErtA10, BGHBHJ107, BGCuponation10, 13f142, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BGHealth06, 00c906, BGHealth10D
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for 2Pcs Oclean P2 Replacement Toothbrush Head.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).