Well back in the day, I did NOT have any 50 level characters, nor did I have friends flinging inf at me. So this is what I did back then.
Collect all the exploration badges. Doing a zone gets you Merits (10 per zone, I think?).
Once you are at the level where the street mobs in Perez are blue and green to you, turn off XP and just street hunt. The single most valuable piece of salvage outside of the Rares drops from the Hellions ("Luck Charm"), it is a common, and you can clean up. Not only will you be getting double inf, but blue and green mobs drop the same amount of salvage as red and yellow ones. Back on live, Luck Charms sold for obscene amounts of inf. I'm going to presume the same holds now.
Run short AE arcs for tickets. Use the tickets on recipe and salvage rolls. If you are between 11 and 25(?) on recipe rolls you stand a really good chance of getting one of the anti-knockback Defense or Resist Damage recipes and those sell for Quite A Lot.
You always have the option to turn off XP for double inf.