Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
Coupon (624.68 USD): MVC8SPRING
(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): BGOP8TG12, 13f142, BGOP8T12, BGOP8T12IS, BGOPT8T56, BGOPT8D1256, BGOP8TT256, BGOPTI256, BG880bdb, BGOP8TI256, BGba99ec, BG82d92a, BGOP28TI256, BGa230f3, BG09df9d, BGc273bc, BG0ff2ad, BGd138ba, BG9cf12a, BG4a4185, BGbcafa2, BG615a35, BG939dba, BGffb56a, BG7a97fa, BG46ac0a, BG9084a4, BGb84dbc, BGOP8T17, BGOP8T17EU, BG1de9f6, 6GSGIT, BG2a0082, BG5fdcf7, BG060f5a, BG0801b8, BGae6726, BG84b1f2, BGcbe01e, BG7a6db4, BG5ffcbf, BG2ae944, BG61b86d, BG882d4f, BG8c4689, BGb57661, BGaac117, BG36c11f, BGdaf962, BG2a8584, BGd53b5c, BGa882ab, BGa0ef82, BG5ce27c
(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 OnePlus 8T 5G Global KB2003 12/256GB.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).