Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (39.09 USD): BGCAR639
Coupon (40.47 USD): BGSCM11
(CouponsFromChina.com tip: apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGTester26, BgAuMotor, BG18SFMP, BGTester29, BGAutos, BGTester68, BGTester69, BGTester123, BGCARELEC, BGAFF10OFF, BGSABAUM26, BGTester19, BGwhielabel, BGba0e9d, 13f142, BG10OFFAFF1, BANGGOODSD, 6GSGIT, BGf6e31f, BG273d3d, BG00c906, ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, BG1b524a, BG9e6ad6, 2203ActiesNL, MVC8SPRING, BG1e7a3b, BG057edd, BG9287e9, BG7ebd3e, BG4cb982, BGfc41d0, BG26c571, BGb767ba, BGd09721, BG85100e, BGd2ddd0, BG6a3ea0, BGdf556b, BG60e54d, BGb57e8d, BGiMars2022, BGb8699f, BGd46a80, BGcd5f65, BGac645c, BG8227e9
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for Micro-200 Pro 12V Battery Tester.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).