Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. I have no active coupons for you right now.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGDJI10, AFfbG10, BGDJI8, BGD10, BGDJIS10, BGDJIS1, BGDJI12, BGS1Robot, BGS110, BGS113, BGEDK12, bGhOnEy10, BGDJIS11, BGDJI7, BGS1ROBOT1, bgshOOp10, BgcLuBofErtA10, BGBFRO3, BGCM1132, BGAFF10OFF, BGCuponation10, BGDJI527, 7bcdf9, BGHONEY2110, BGDJIS423, BGd79389, BGb2f2f6, BG33bf59, BG4f86f5
(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 DJI Robomaster S1 STEAM FPV Robot.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).