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 (40.53 USD): BGe46870
Coupon (42.33 USD): BG00c906
(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): BGZH151, BGTS204, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGTRIP01, bgshOOp10, BgoFErTaSchInA10, BgcLuBofErtA10, BGTY742TRL, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BG4d9120, BGAlerabatod, 00c906
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for Xiaomi 90FUN Travel Conversion Plug EU US AU CN UK Type-C is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).