After you complete the game, go to Nessa (Saturn) Area 3 and search the area with the Gejio Spectrobe. Gejio has a search area of 7 and can only find minerals. If you search long enough, you will find a mineral called Gold. This mineral is the most valuable in the game and can be sold for 100,000 Mesa.

Once you find the cube that lets you use the WiFi connection, go to the WiFi machine. Then, go to Nintendo WFC download on Fridays to get DL points; you can get ten each Friday. Use the DL points to get two minerals on your bottom screen. It will be a sapphire and pearl. Next, go to the fourth planet, Area 1. Go the place with a group of people. Then, turn left and then keep going; then go up, then downstairs. Talk to the person near the wall. He will buy the minerals and give you lots of money. Then, change the system date on your Nintendo DS to the next Friday to get more DL points. Repeat this process as many times as desired.