While common salvage is an annoying problem, would much rather have the devs working on other things than this.
As for common salvage not selling quickly? I put it up for 250 and it is gone within minutes; so unless you are listing it at some absurd amount not sure why yours doesnt move.
Night ward will get you to 41-42, if you save Trilogy/Fireball for after outleveling the repeatable contact; then to get to 50 you have to option of flashbacking the arcs you missed (via SG Pillar). My Praetorian is currently 47, with 1/2 of Imperial city's arcs left and most of Neutropolis left