Aliexpress
Click here… to search for Tigernu T-B3164 21L 17 inch Backpack Gray on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (55.14 USD): bgssaff9
Coupon (56.35 USD): aff7off
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 19BGTD, e2bcea, TTxBG10, BG3CSUM
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Here is price history (for all/most countries) for Tigernu T-B3164 21L 17 inch Backpack Gray.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).