If you’re looking for an iPhone 11, the O2 “Like New” site is well worth a nose. They’re offering the 64GB iPhone 11 in a range of colours (black, green, purple, white, yellow etc) and you can bag one for £470.
To get that price, you’ll need to click the “Pay in full” option, which is tucked under their list of monthly plans. Click the iPhone 11 colour you want, then “Pre built plans” and then scroll to “Pay for your device in full”. It looks like you’ll also need to at least pay for one month on their monthly talk plan – minimum is £16 on that. Either way, for sub-£500 that’s a jolly good deal for a phone which is still selling for £599 on the Apple site itself.
I’ve just had a look elsewhere (MusicMagpie etc) but couldn’t find a price near this.