Game Shark Codes (Japanese - NTSC - version):

Infinite Money 
800CE11C 896F
800CE11E 0001 

Set Upgrade Credits = 168 (Press L1) 
D0053570 0004
801FFD8C 00A8 

Set Upgrade Credits = 0 (Press L2) 
D0053570 0001
801FFD8C 0000