Spirit Airlines charges a fee for unaccompanied minors, typically ranging from $100 to $150 per child each way, depending on the route and other factors. This fee covers the airline's assistance and supervision for young travelers aged 5 to 14 years old. It's important to note that fees and policies can vary, so it's recommended to check directly with Spirit Airlines or review their official website for the most up-to-date information before making travel arrangements for Spirit unaccompanied minors.