Some were subsidized and you can't change carriers and are stuck making payments for the service.
Until the details are known it's either a great deal or not so great.
There's nothing wrong with the phone, the price is that low, because our friends don't need this phone and they sell it, because they are going to buy an iPhone XS Max, is that a good deal? The iPhone is in perfect conditions, Ive seen the phone, its working properly and it its like new, i got an iphone 7 right now and i wanted to upgrade, and they offered me this deal, is it worth it?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic