You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Color: White/Pink/Green, Gear Adjustment: 5gear, Voltage: 5V, Power Supply: USB, Shell Material: ABS, Power Cord Length: 1.5m, Constant Temperature: 55℃, Power: 20W
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($13.60): BGeaf456
2. ($14.20): BG00c906
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG5be493, BGwhielabel, BG4a794c, 13f142, BG10OFFAFF1, BG166b1a, BANGGOODSD, BG2a6a0b, 00c906, ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, 2203ActiesNL, BG1efeb0, 8Couponsde, MVC8SPRING, pROMo8cuPoN, BGJUNEGSG9, Cuponation9, 9OFFSUMMER, BGAHPU13, BG8ReviTrage
(probably won’t work, but you can try them out)
Price history and price alert
Do you need price history chart (for all/most countries) for 3life S07 Constant Temperature Cup Heating Mat 20W? There we go.
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)).