Abandoned Bunker

To start this quest you need to talk with a trapper in "Darkwaters" bar near the south entrance of the Junktown. The quest does not register in your Pip-Boy so pay attention to his instructions in dialogue. He sends you to Boneyard to find a man with a scar on his face. You'll know when you're searching in the right area when you get dialogue about it with the NPCs you ask. You'll follow his path from there to Necropolis. Find a ghoul named Wally who is in Watershed. The bunker base costs 350k caps.