Aliexpress
Click here… to search for Xiaomi QC3.0 X2 Metal Dual Car Charger on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (14.39 USD): BGAFF10OFF
(CouponsFromChina.com tip: put item in your cart and apply coupon code there 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): TTxBG10, BG3CSUM, AFfbG10, bGpAnDacHeCk, BGVDay10%off, bGhOnEy10, BGXMI15, BGdragonBoat, BGXiaomidual, BGXiaomi88999, bgshOOp10, BgoFErTaSchInA10, BGHALLOWEEN, BgcLuBofErtA10, BG20CHARGER, BGMBCBLE
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Xiaomi QC3.0 X2 Metal Dual Car Charger is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).