Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (104.06 USD): BGAlerabatKL
Coupon (104.06 USD): BGd173b4
(CouponsFromChina.com tip: just apply this code in your 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): 7d18f7, BG4BW25, BGLOAC1, 13f142, BGa0b145, BGBuscape01, BG651551, BGBRPL2, BGHOTSHOP15, BG53e9c8
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for TRN T300 TWS Earphones.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).