You must have DLC3 (Secret Armory).
1. Wealthy and strong new character: get a character to Fyrestone, once it lets you, go to Tbone Junction and loot everything there: 2 silver, 2 red chests, lots of lockers full of cash, exit and then repeat. Your new character will slowly level up and easily get 100,000s of dollars.
2. Farm Tbone at appropriate levels: in PT1 (playthrough 1), Tbone will spawn level 27-40 weapons and gear. In PT2, it spawns 48-51 level gear.
Simple run: Hit any/all lockers, but this is the chests route: Spawn, go through the 2 doors, make a left, go to where the bounty board is (Claptrap is there). On top of that building is the first silver chest, jump on stuff to get up there, it should be obvious and easy.
Then, head back the way that you came and continue up the hill. As soon as you get to the top, stay left along the curved edge of the top part (not inside where the first Ninja girls attack) and keep looking down and left for the silver chest below you. Drop to it.
After that, drop to the catwalks below and loot everything there, including the first red chest. Head up and out of that area. You will emerge next to the save pole.
Make a right, make a right down the street (heading N) and get in the elevator on your left. Take it to the top, walk straight out past the guy sitting there, see the yellow bus? To the right of that is a walkway that ends and there is a boat below you with the second red chest, fall to it. After that, exit/save/repeat.
If it is a new character, be careful not to trigger the Ninjas. They are easy enough to escape from though.
If at the correct levels, remember to hit up the Dr Zed machine up top (left from elevator) and the gun machine in the easternmost part of Tbone J.
[more cheats for Borderlands here]