For shipments inside the US, you can choose between USPS First Class Mail (Standard) and USPS Priority Mail (Express). Standard is a flat rate of $4.00, usually takes 3-5 days and includes Delivery Confirmation. Express is a flat rate of $8.00, usually takes 2-3 days and includes Delivery Confirmation.
For international shipments, you can choose between Airmail (Air Service) and Express Mail International (International Express). Air Service is a flat rate $6.00, takes 7-14 days, but is not trackable or insured. International Express is a flat rate of $30, takes 5-7 days, and is trackable and insured. If you don't mind waiting, Air Service is a great value.