To easily get money and items, in "New Haven", go to the save/transport post near "Scooter" and save the game. There are two red chests and three silvers chests in town. After looting all of them, save the game and then exit. Reload the game and repeat the process. The following are the locations of the chests:
Red Chest #1 - On the roof of the building right of the save post. Go to the side with the yellow barrel, and jump few times.
Silver Chest #1 - From the save post, turn left and go upstairs. Continue in the same direction, cross the wood plank and then jump the railing to the other building. Turn right around the corner.
Red Chest #2 - Starting from Silver Chest #1's location, jump on the red tarp hanging over a small platform. Turn around and you will see the chest.
Silver Chest #2 - After completing the Claptrap Rescue this Chest will be in a little shed across the courtyard from the Bounty Board.
Silver Chest #3 - From the save post, go forward and upstairs where the dollar sign and arrow are. Jump on top of the washing machine, then on top of the roof with the antenna. The Silver Chest is located behind it.