I have just checked coupons. The lowest price I could get is $15.99 for Portable Cordless Neck Heater (in Banggood). Go down and check coupons out. Remember to check price history if it is available. You probably want to know what is the best price?
Latest coupon and price update (UTC):
Portable Cordless Heater Neck Heater Personal Wearable Electric Heater 4-Speed Temperature Cordless Charging Personal Heater Outdoor Heater – Grey
Banggood ($15.99)
Banggood warehouse is located in China. What about the price? Looks like this is great price. I didn’t track lower than that in CouponsFromChina database ever. Basically there’re 2 active coupon codes available!
Link: Banggood product page
Price without coupon: $22.99
1. ($15.99): BGb465b7
2. ($17.99): BGdd97c4
apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop.
This is the best price ever noted in my database!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for Portable Cordless Neck Heater is here.
Price records source(s): Banggood
Click on image to enlarge. 
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)).