Currently level 10 and Can't seem to access the black market. Also if someone could explain the Eriudium to me and how it's used. I only played the first Borderlands to roughly level 20 or so and it was a while back. Thank you! --- "Hugh is the most reasonable person i've seen on gamefaqs in a while. It's refreshing." -Hardsix.
You'll be introduced to it as soon as you reach Sanctuary. The story quest will guide you right to the NPC who sells upgrades for Iridium. He's the "black market" and is basically just a change from BL1 so that you don't have to spend loads of cash in early game to upgrade inventory and clip size.
A couple tips though:
- Loot EVERYTHING. Iridium can be found anywhere (only place I've yet to see it are in the small cash boxes) and it's quite rare early in the game. Sometimes, if you find it in the larger containers, you'll even get stacks which basically equates to a free upgrade.
- Ammo is a bit scarce early in the game so, unless you HAVE to have 4 low level characters decked out with the best stuff you find on your main (via the bank [which you also find during Sanctuary]), upgrade your two favorite gun types' clip sizes ASAP. Nothing worse than wasting ammo during a bandit camp raid only to be met with a hardcore firefight soon after.