Giffgaff have “like new” 128gb 13 mini for £499. Comes with 2 years warranty. Only downside is that you have to purchase a sim card at £10 and this is a rolling contract, you can cancel this immediately after purchasing to ensure you don’t have a recurring direct debit. I personally have never had an issue with giffgaff and when purchasing as new they have been flawless 😄