While cash is the most immediate form of payment and accepted everywhere (in fact preferred in a number of cases), credit cards and traveller's checks can be an alternative. But there are pitfalls.
Passports issued to children under age 16 are valid for 5 years. Children under 16 must renew their passports in person and follow the same guidelines as when the passport was first issued, including being accompanied by parents or guardians. Two current passport-sized photos must be included with the application.
Get ready to have your patience tested. Acquiring or renewing a child's passport is no walk in the park. Over the past few years, new requirements have been added in an effort to combat child abduction and trafficking. The new requirements mean more work for parents to acquire passports for their children.