Basically copy coupon, view price history or create e-mail price alert. Do you want to know what the best price is?
4x HEPA Filter, 4x Main Brush, 8x Side Brush
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 Europe 
. I don’t really know if this price is reasonable, coz there’s no price history in my DB. One coupon is available. Cool!
Link: Banggood product page
1. ($22.61): BGAHPU13
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): BG16PCSES, BGHOMEA13, 13f142, BG10OFFAFF, BGEFDRSV, BGwhielabel, BG10OFFAFF1, BGe99602, BGd4fb13, 00c906, BGPT0127, BG00c906, BGJUNEGSG9, Cuponation9
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Well, you won’t see price history chart, coz we have only 1 database record for this item (and price was $18.99).
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)).