Basically copy coupon, view price history or create e-mail price alert. You probably want to know what is the best price?
Size：138*176mm, Side plate: 2.5mm, Arms plate: 5mm, Top plate: 2.5mm, Full 3K Carbon Fiber, Motor to motor：225mm, Bottom plate: 2.5mm, Mounting Holes: 30.5*30.5mm/20*20mm, Protect plate: 2mm
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood.
Link: Banggood product page
Price: $-3
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGMARK4HD, BgoFErTaSchInA10, bGhOnEy10, BgcLuBofErtA10, BGBFGEPHD, 7bcdf9, BG10RACING, BGAFF10OFF, BGMATT7, BGDAVIS, BGGEP30, BGa1204e
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for GEPRC MARK4 HD GPS 4S 225mm Drone BNF is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).