I found that my Fairphone 2, even after I considered it obsolete for my usage, was an easy trade-in at a price point that could only be explained by the person caring about keeping it around for a good while.
Apart from the hardware flaws it is an excellent hand me down, as are all Fairphones. But so are all iPhones. Its just that recent ones are tougher to repair, making them less good of a hand me down.