Download the "Stuff" mini-game to your VMU. 
Then, save your game. Now sell everything 
you have and go to the Monster House. 
Here, buy as many tokens as you can afford 
and put them in your VMU. Reset the game, 
then load the game file. You should have 
money, your items and tokens. Sell the tokens 
and then save the game. Go back to the Monster 
House to and do the same thing as much as you 
want.