Product size (Lx Wx H): 200x 2.5x 0.21cm, Type: Robot Anticollision Magnetic Tape, Package weight: 399g.
Just check coupons out (with price alert and history). What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($19.03): 8Couponsde
2. ($19.03): MVC8SPRING
3. ($19.24): 2203ActiesNL
4. ($19.45): BG00c906
you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGBFCR02, BGBFAFF2019, BGCITYADS2019, aff7off, 2020CNY, BGVDay10%off, BGHOMEAPP, BGTT10, bGhOnEy10, BGAFF7OFF, BGSS10%SW, BGXMRVC, BGHOMEAPP12, BGHome15%, BGHOMEAPP13, BGHOMEA13, 13f142, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BANGGOODSD, 00c906, ADMITAD2212, Terence, Tabby20, BG1efeb0
(probably won’t work, but you can try them out)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – 2m Mi Robot Vacuum Invisible Wall Tape [EU] ($-3)
Price history and price alert
Here is price history (for all/most countries) for 2m Mi Robot Vacuum Invisible Wall Tape. The lowest price was: $4.99.
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)).