Connecting interface: 3.5mm, Type-C, Driver unit: 57mm, Frequency response: 15~25000Hz, Impedance: 16ohms, Sensitivity: 116dB, Bluetooth Version: V4.2, Battery Capacity(mAh): Built-in 650mAh Li-ion Battery.
Price history, coupons and price alert are available on this page. Do you want to know what the best price is?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. 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
1. ($57.74): AFfbG10
2. ($57.74): EARSP11
3. ($59.16): 7d18f7
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 and https://couponsfromchina.com/short/i1u
Old coupons (from the oldest to the newest): d4de0b, TTxBG10, BG3CSUM, BGBFAFF2019, BGCITYADS2019, BGVDay10%off
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Bluedio T4 Bluetooth Headphones. The lowest price was: $25.99.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).