Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (947.43 USD): Email5
Coupon (947.43 USD): bgshOOp10
(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): affiliate6, aff7off, bgssaff9, od7off, BGaDmITAd, 7bcdf9, BGBFAFF2019, BGCITYADS2019, BGMPB2020
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for HUAWEI P30 8/256GB Black is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).