Almost every kid I know gets their parent’s old phones. Apple made a major effort to extend the supported usable life of their phones several years ago and it’s paid big dividends in terms of getting the kids started on iOS. A brand new $400 SE can easily be expected to give 5-7 years of service, which brings the starting price down to $60-80/a to say nothing of the used market. It’s hard to even argue that Android is the cheaper option unless you don’t mind running insecure OS versions for several years.