Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (269.99 USD): bGhOnEy10
Coupon (269.99 USD): bgshOOp10
Coupon (278.99 USD): BGAFF7OFF
(CouponsFromChina.com tip: put item in your cart and apply coupon code there 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): aff7off, BGAttitude, bgssaff9, BGss35, BGBCFPV, BGafsv5, BGBCBG10, BGANCB4, BGNNAA5, BGWDDV5, BGWDV5, BGCNA10, BGHU429, bgchinafest, 502C6B, BGOTC21, BGavG14, BGDDEE9, BGDE111, BGBFAFF2019, BGJPBF17, BGCITYADS2019, BGBMRC1, BGBFEVENT1, BG9NY, bGpAnDacHeCk, 2020CNY, BGVDay10%off, BGMPB2020, BGJPFSGR91, BGTHSEP018
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for Fatshark Attitude V5 OLED FPV Goggles is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).