Basically copy coupon, view price history or create e-mail price alert. What is best price?
High-density DuPont Tynex brilliant planting brush, Food-grade PP material with FDA certification
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
Price history (for all/most countries) for Oclean One/SE Replacement Brush Head is here.
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)).