Aliexpress
Click here… to search for Holybro Pixhawk 4 Mini QAV250 Basic Kit Drone on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
Coupon (351.76 USD): Drones6
(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): BGHP4, AFfbG10, Bg30H13, 502C6B, BGBFCR25, BGCITYADS2019, BGMPB2020, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BGRC902, BgcLuBofErtA10, BG10RACING, 7bcdf9, BGDAVIS, BGMATT7
(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 Holybro Pixhawk 4 Mini QAV250 Basic Kit Drone.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).