You can create price alert here, copy coupons and view price history. You probably want to know what is the best price?
Material Polyester, Capacity 20L, Brand Xiaomi, Weight 285g, Size 416x 290x 154mm
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):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
1. ($30.02): Cuponation9
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGXM20L, BGTB635, BGXM738, BGbag20L, bGhOnEy10, BGBAGGE, BGAFF10OFF, BGdragonBoat, BGCAMP01, bgshOOp10, BGHU0008, BGG07905, BGE69343, BGSHHA, BG1111DS14, BGCDC076, BGH5638XM, BGZPBC15, BGDJ510B, BGTY704CP, BGTY107AF, BGVIP68B, BGCuponation10, BGHONEY2110, BG10OFFAFF, BG29b763, BGwhielabel, BGalibuy343, BG8f8428, BG58ab20, 13f142, BG10OFFAFF1, BG4d9120, BGAlerabatod, BG84de95, BGAlerabatdo, BG3b0d87, BG21718b, 00c906, BG8fd4e2, BGe46870, BG7280ff, Tabby20, BG517f5b, 8Couponsde, BG36e006, MVC8SPRING, BGALIBUY3431, BG2bb7a1, BG5d2ea4, hoNEYbGdeAlS, BG073996
(I don’t think these’re gonna work, but you can try ’em out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – Xiaomi 20L Backpack 15.6inch [EU] ($-3)
Price history and price alert
Price history (for all/most countries) for Xiaomi 20L Backpack 15.6inch is here.
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)).