System: H2 OS (Based on Android 9.0), CPU: Qualcomm Snapdragon 845 Octa Core 2.8GHz, Beidou, Accelerator, Glonass, Display: 6.41 inch, SIM Card: Nano SIM card + Nano SIM card, Camera: 20.0MP + 16.0MP rear camera and 16.0MP front camera, Feature: GPS, Sensor: E-compass, 2340x 1080 Pixel Screen, A-GPS, Gravity Sensor, Bluetooth: 5.0, Gyroscope, Light Sensor, Fingerprint Sensor, RAM + ROM: 8GB RAM + 128GB ROM.
Go down and check coupons out. Remember to check price history if it is available. Do you want to know what the best price is?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. 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
1. ($369.99): BGUSOP6T
2. ($450.99): 7bcdf9
just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): 11BGR6P4, 11BG6T8, BG116T8, 6T11BG8, 12bgop5, 12MCOP6T8, 1BGOP6T2, Alibuy9137, 1BGOP6TA, 2BGOP6TB, 62ca20, 3BGOP6T, JPBG128W, koninimbesinop6t, f262fb, JPBG128h, plfonall, 19BGOP6T, 4OP6T, 4bgop6t, 5BGOP6T, bg845, BG5OP6T, BG6Tplus01, BGDJOP6T, BGOP6T527, BGONE11, BGaDmITAd
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for OnePlus 6T 8/128GB Midnight Black. The lowest price was: $369.99.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).