after you talk to the reception lady at the torture rack about fawn, you have to go to the hint guy in the little homeless camp place, and give him something.
i gave him an apple, so i dont know if it was a special occasional happening but after that he'll tell you that the black market sells to those deemed "cool" by them, and he says you seem cool, so he gives a good word to them.
after that, you can go to the junk seller and he should have the four different types of counterfeits.
(i bought all four, and do not know how to use them. using any of them at the upper ark gate just gets you arrested lol)
hope that helps!