The 'Assault on Dragon Keep' DLC or what is sometimes called The Unassuming Docks (of potentially little importance) changed all that. Of course, building up the cash to build up one's Eridium is difficult in normal game play. For low level characters, those upgrades are crucial: backpack slots, ammo limits, grenade count, etc.
If you had the cash, you could build up a big stash and upgrade your character attributes. When I first started playing-years ago-I figured out that you could use the slot machine's at Moxxi's to build up Eridium. Eridium comes in purple bricks in Borderlands (I'm only talking about Borderlands 2 here, but I'll leave out the 2 to avoid going nuts) that you use to upgrade your character at Crazy Earl's in Sanctuary.
