Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. You can get coupon down below.
Link: Banggood product page
Coupon (164.99 USD): 7d18f7
(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): od7off, BGBFAFF2019, BGCITYADS2019, 7bcdf9, Email5, BGAFF10OFF, bgshOOp10
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for OPPO Realme 3 3/32GB Global.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).