On the Sender Station, build up some money by buying Shamfoofa Shells from 
Sandie (in the Starports) and selling them to Vince (in the Longe of Commerce).
When you manage to stock up enough money, buy about 400+ or 500+ shells from 
Sandie again. You must have at least 1 Life Flower Petal to do this trick. 
When you try to sell your rare item (the Flower Petal), you will notice that
you can only sell a Twin-Scaled Underplate instead. Sell this item to get 5000
loonies. By doing this, you only subtract 1 Shell from your inventory. Keep 
repeating this to gain a large amount of money.