Aliexpress
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
Coupon (116.79 USD): BGAFF10OFF
Coupon (116.79 USD): bGhOnEy10
Coupon (116.79 USD): bgshOOp10
(CouponsFromChina.com tip: paste coupon code in your cart and click Apply 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): BGV007BOAT, BG20OF681, AFfbG10, BGFLYB, BGTEC071, 502C6B, BGBFAFF2019, BGCITYADS2019, BGVDay10%off
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for Flytec V007 500m RC Boat.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).