you are right about the money unfortunately if you don't have the money to keep the immigration happy to give you the visa you will be required to leave the country, or don't touch the money until you have the visa
Just do the yearly visa application and you will just leave the country when you are ready to travel back home, your visa will be just be cancelled once you leave the country
This will help you, but depends on the thai immigration office you are going to use, I would recommend that you go to the immigration office to find out if they have any other requests