To unlock ALL of the costumes for each character with only 30pts save the game before defeating the last enemy on map. Then defeat the last enemy and skip through the story to get to the suit shop. Select a 30pts suit and buy it (e.g commando suit) and then reload the last save file. Go to the suit shop again and you will have 30pts left with the commando suit already purchased. This can also be done with the 10pts suits when you have 10pts.