When I was updating this page the price was $12.99 for Car Automotive Refractometer (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Latest price update (UTC time):
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
Banggood ($12.99)
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood. The question is – is it a good price? From what I can see this price is higher than average price ($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
(I don’t think these’re gonna work, but you can try ’em out anyway)
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
Check out price history chart (for all/most countries) for Car Automotive Refractometer.
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)).