Speak to Eva Levante in Tower North at the Tower.
"Miss Levante reports merchant activity across the tower up something like 400 percent since we joined the Vanguard. Golden Age relics, engrams, Hive foci from the edge of the Light, broken bits of constructs, Cabal intel, Fallen weapons and armor. Pushing back against the Darkness and making a little Glimmer can go hand in hand, I guess."
—Ghost