Aliexpress
Click here… to search for Bluedio T4 Bluetooth Headphones on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (57.74 USD): AFfbG10
Coupon (57.74 USD): EARSP11
Coupon (59.16 USD): 7d18f7
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): d4de0b, TTxBG10, BG3CSUM, BGBFAFF2019, BGCITYADS2019, BGVDay10%off
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Bluedio T4 Bluetooth Headphones.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).