ATM you can buy USB Warm Up for 14.06 USD (in Banggood). Basically copy coupon, view price history or create e-mail price alert. You probably want to know what is the best price?
Latest coupon code price check (UTC time):
Banggood (14.06 USD)
Banggood warehouse is located in China. Is it good price? Hmmm, price is higher than average (which is 13.01 USD right now), so better set price alert down below… I am tired of searching coupons, but I found one for you…
Link: Banggood product page
Price without coupon: 15.62 USD
Coupon (14.06 USD): BGAMMT03
(CouponsFromChina.com tip: apply code in your basket (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): BGSCM75, BG589b2e, BGSCM11, BGCAR639
(probably won’t work, but you can try them out)
Aliexpress
Click here… to search for Electric Battery Heating USB Warm Up Vest on Aliexpress
Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for Electric Battery Heating USB Warm Up Vest.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).