Aliexpress
Click here… to search for Oneplus 7T 8/128GB Blue on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Hong Kong. As you can see I didn’t find any active coupon for this product right now…
Link: Banggood product page
Price: -3 USD
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
Old coupons (from the oldest to the newest): BGOP7T128, od7off, BGBFAFF2019, BG3COP7T8128, BGCITYADS2019, BGBF7T8128, BG7T128BFL, BGBFSP7T8128, BG12OP7T128, BGAOP7T8128, BG1OP7T8128, Email5, BGSFOP7T128, BG2OP7T128, BGDJOP7T128, BGDJOP7T12, BGR7T212, BGOP7T36, BGJP1287T0, BGWK7T, BG7T128320, BG7T402, BG7TDP128, BG7T12814, BG7T128G
(there’s a little possibility that old coupon will work)
Price history and price alert
Check out price history chart (for all/most countries) for Oneplus 7T 8/128GB Blue.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).