Probably the best deal IMO I can find right now on an iPhone. ATT currently has the iPhone XS for $1/month for 30 months ($30 total) with no trade-in required. Obviously, it requires a line of service to be activated and port in of your existing number but still a really good deal if you need ATT service and a new phone. Retail price is $699 so I'm pretty sure if you cancel early, you're responsible for the balance.
Link may not take you right to the deal due to the way ATT does their website but it's there.
Combine this deal with a FAN discount if you're a first responder, school teacher, nurse, etc. and you can have 4 lines unlimited with 4 iPhone XS' for $109/month. $105/month for the discounted plan and 4 iPhones at $1/each. I really don't see a better deal out there right now considering the device cost and no trade-in required.
*Edit. This is a great deal for a multi-line plan. Not so much for single line plans.