Just check coupons out (with price alert and history). What is the best price?
Connection: Bluetooth 5.0 (for Switch / Android / iOS); Wired (for PC), Net Weight (1pc): 156 g / 0.34 lbs, Vibration Motors: Yes (for Switch and PC only), Product Size (1pc): 143x83x53 mm / 5.63×3.27×2.09 in, , Battery: 600 mAh rechargeable Lithium battery, Wake up Switch Console Function: Yes, Six-Axis Gyroscope: Yes (for Switch only), Auto-sleep Mode: Yes, Working Platform: Switch / Android 9.0 or above / iOS 13 or above / Windows 7/10 or above, Auto-Combo Function: Yes
Aliexpress
There’re some similar (or not) items on Aliexpress
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. We have found one coupon for this product!
Link: Banggood product page
1. ($50.75): BG589b2e
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG3a7160, BGAlerabat5, BGe245d0, BG68bad2, 8BGwbg2204, tRaDetRaCKeR, BGVGAMES, BG8ReviTrage, Cuponation9, 9OFFSUMMER, BGVDGA07, BG717000
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for GameSir T4 Mini Bluetooth Controller Gamepad.
Price records source(s): 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)).