Weight Approx.1000g, Capacity 32L, Color Grey, Blue, Material Polyester, Size 48x 23x 29cm / 18.90x 9.06x 11.42inch.
Basically copy coupon, view price history or create e-mail price alert. 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 price update (UTC time):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
1. ($77.21): BG10OFFAFF1
you should apply the coupon 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/i1u
Old coupons (from the oldest to the newest): BGOD1, 2019SPEDM, BGss506, AFfbG10, BGcamp305, 502C6B, BGBFAFF2019, BGCITYADS2019, BGVDay10%off, BGOL786, BGAFF10OFF, BGTT10, bGhOnEy10, BGdragonBoat, BGCAMP01, bgshOOp10, BgoFErTaSchInA10, BgcLuBofErtA10, BGZPBC15, BGTY704CP, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG0b82e2, 13f142
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi 32L Shoulder Backpack. The lowest price was: $50.06.
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)).