Go to Three Horns Valley, go to the hideout where you fight the Bad Maw boss. Big giant guy with a hoodie on. Kill him, and pick up the eridium. Lave that area and head towards Bloodshot Stronghold, Once there Save & Quit. Load up your game again and return to Three Horns Valley kill Bad Maw Boss pick up eridium and rinse and repeat = PROFIT
I have been doing this, but at the Terramorphous boss fight. Same steps basically, more Eridium, but takes a little longer.
