I just took a look at Ideal World on ITV, and they're flogging the iPhone SE (refurbished and pre-owned) for £170 quid. A three year old smartphone with minuscule 4inch display. Even the overnight infomercials on much smaller channels don't scrape the barrel this much!
So this is what late nights on ITV has come to ... 2-3 hours of a 3rd-rate shopping channel starting with a bunch of 2nd-hand iPhones!
The small display is because the phone was aimed at iPhone users wanting an upgrade without an increase in screen size. It still supports the latest version of iOS, and is probably the cheapest entry point for the modern iPhone experience.
The phone is refurbished with genuine parts - you're paying perhaps £20-£30 more than the equivalent item on eBay, but you're not risking buying a stolen phone and you have better options for recourse should it be necessary.
Would I buy one? No. But the way you describe it is hardly fair either. If you want awful iPhone prices, take a look at QVC's iPhone 7 prices...