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 (248.76 USD): BGDAVIS
Coupon (251.46 USD): BGMATT7
(CouponsFromChina.com tip: you should apply the coupon 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): BGWKM630, 502C6B, AFfbG10, BGBFCR25, BGCITYADS2019, BG-M630NEW, BGVDay10%off, BGM630FEB, BGMPB2020, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BGRC902, BgoFErTaSchInA10, BgcLuBofErtA10, BG10RACING
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Diatone 2018 GT-M630 Normal X Drone PNP.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).