Aliexpress
Click here… to search for GameSir G4s Gamepad on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (38.18 USD): elec
Coupon (38.18 USD): BGAFF10OFF
Coupon (38.18 USD): BGTT10
Coupon (38.18 USD): bGhOnEy10
(CouponsFromChina.com tip: put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): 20eb83, 502C6B, e2bcea, AFfbG10, f3ee93, BGE13, BGAMEPAD, BGVDay10%off
(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 GameSir G4s Gamepad.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).