Here’s how to get the key to the black market shop to get lots of free goodies including a Pistol, Pistol Bullets, Grenades, Sticky Grenades & more!
Can be done in “Mission 02: Edge of the World”. At the start of the second mission go through the bloodfly infested building all the way to the upper floor. Here you will find an infected enemy and the key to the black market shop. Pick up the key and return to the black market at the start of the mission. Climb through the window behind the shop and open the door with the key.