The US carrier T-Mobile is offering US$580 in bill credits when a OnePlus 6T is bought on a monthly plan today (November 26, 2018). However, this deal requires an eligible device to trade in and for the customer to add a new line to their account. It also applies to the 8/128GB variant of the 6T only.
https://www.notebookcheck.net/Get-the-OnePlus-6T-on-T-Mobile-on-Cyber-Monday-for-free-sort-of.369251.0.html