Aliexpress
Click here… to search for GameSir T4 Mini Bluetooth Controller Gamepad on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. Well, there is one coupon available right now.
Link: Banggood product page
Coupon (50.75 USD): BG589b2e
(CouponsFromChina.com tip: apply it 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): BG3a7160, BGAlerabat5, BGe245d0, BG68bad2, 8BGwbg2204, tRaDetRaCKeR, BGVGAMES, BG8ReviTrage, Cuponation9, 9OFFSUMMER, BGVDGA07, BG717000
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Do you need price history chart (for all/most countries) for GameSir T4 Mini Bluetooth Controller Gamepad? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).