$12.99 – Car Automotive Refractometer (Banggood, Aliexpress: Ethylene Glycol: -50°C-0°C (0–70%), Propylene Glycol: -50°C-0°C(0–70%), Resolution Factor: 5°C / 5% /, (ATC) Temperature Compensation Range: 10°C-30°C (the best price with coupon)).
ATM you can buy Car Automotive Refractometer for $12.99 (in Banggood). Basically copy coupon, view price history or create e-mail price alert. What is best price?
Latest coupon and price update (UTC):
Banggood ($12.99)
Banggood warehouse is located in China. CouponsFromChina software could not find any coupon for this product in Banggood. But wait a sec… Is it a good price? Maybe there’re no more promotions for this item, because current price is higher than average (which is equal $12.02)
Link: Banggood product page
Price: $12.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG20236Tool, BGTOOS729
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
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
Here is price history (for all/most countries) for Car Automotive Refractometer. The lowest price was: $11.04.
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)).