Aliexpress
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
Coupon (24.64 USD): BG073996
Coupon (26.38 USD): Cuponation9
Coupon (26.67 USD): BG8ReviTrage
(CouponsFromChina.com tip: this code has to be applied 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): BG2bb7a1, BG38b8d9, BG5d2ea4, BGRSUNBAG, 9OFFSUMMER
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for 15L Camping Thickened Thermal Bag is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).