You can create price alert here, copy coupons and view price history. You probably want to know what is the best price?
Polyester lining with water-resistant 650D oxford outer cloth, durable, anti-scratch and lightweight, 26L large capacity and 30kg load-carrying capacity, it can hold 15.6 inch laptop easily
Aliexpress
There’re some similar (or not) items on Aliexpress
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Price history and price alert
It doesn’t make sense to generate price history chart, because there is one price record which is: $39.99.
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)).