https://www.theguardian.com/technology/2017/oct/17/iphone-x-apple-how-to-sell-old-smartphone-new-release-november

Apple’s hotly anticipated smartphone is coming in November and selling your existing iPhone is one way of paying for it. But timing is everything

The iPhone X is coming soon, and if you want to be able to afford it, you have three options: travel back in time and buy a shedload of bitcoin; sell a kidney; or sell your existing phone and hope you get a good price.