I discovered this glitch in the system while buying my first avatar and I've used it many times to increase my gold. First you need to save up 10,000 gold to buy a Yellow Flag. Then you need to take off all your avatars except for the Yellow Flag. THIS IS IMPORTANT!!! YOU NEED TO HAVE THE YELLOW FLAG EQUIPPED. Once these steps are completed you are ready to make some gold. The way the glitch works is by some parameter error which replaces the "avatar name" field with a numeric field of up to 6 digits. In order to get free gold you need to send any avatar to "SupplyStore" and you will receive an amount of gold equal to the numeric value of the avatar's name by the next server update (the server updates daily).
For example, if you send a "Space Helmet A" avatar, you will receive 191,601 Gold!!! That's S = 19, P = 16, A = 01. The amount of gold depends on the first 3 characters in the avatar's name.