Right now the best price with coupon code for 12V Auto Brake Fluid Tester is $23.39 (in Banggood). Price history, coupons and price alert are available on this page. Best price?
Size 6.14 inch*2.17 inch*0.94 inch, Name Brake Fluid Tester, Test Range DOT3、 DOT4、DOT5.1, Model BF200, Color Gray and black, Battery 2 pcs AAAA batteries (not included), Material ABS, Temperature -10°C~50°C, Display High resolution screen
Latest coupon code price check (UTC time):
Banggood ($23.39)
Banggood warehouse is located in China. Price? Well, this price is higher than average price ($19.66) Only one coupon available!
Link: Banggood product page
Price without coupon: $25.99
1. ($23.39): BGAMMT03
coupon code has to be applied in shop’s 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): BGf475ef, BGSCM75, BGf6b5cc, BGSCM11, BG6aefd2, BGCRT313
(there’s a little possibility that old coupon will work)
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 12V Auto Brake Fluid Tester 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)).