Aliexpress
Click here… to search for Lipo-Battery Explosion-Proof Bag on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (9.55 USD): BGGAL8
Coupon (9.55 USD): BGRCParts8
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): Parts8, BG9NY, 2020CNY, BGVDay10%off, BGOTC21, bGhOnEy10, BGTT10, BGSS10%SW, BGRCBC7, BGAFF10OFF, BgoFErTaSchInA10, BgcLuBofErtA10, BGBCSpring1, BGDAVIS, BGHONEY2110, BGRCBC11, BGSFBC1, Tabby20
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Lipo-Battery Explosion-Proof Bag is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).