What are the fees for an agency to apply for a 30-day extension in Thailand?

The fees for using an agency to apply for a 30-day extension in Thailand vary, with reported costs around 3,500 to 4,000 baht, including a separate immigration fee typically set at 1,900 baht. Many comments suggest that applying in person at an immigration office is straightforward and significantly cheaper, as the extension itself costs only 1,900 baht without additional agency fees. Users also note that while agents can save time, the process can be completed independently with minimal hassle.