Good topic!
Black market is something that is gonna arise as the situation going down, and one thing is for sure: it will exist no matter how hard situation is.
I was living for some time in conditions that looked like some weird movie, but black market was there in one or another form.
So it will be there.
Only few rules (there are many):

  • no rules!
  • very often you need to look like you do not want thing in order to get it
  • everything is for sale, everything
  • everything is negotiable
  • it is not like in movies
  • if you are smart (can “predict” what is coming) you can do very good
  • watch out for way too good deals (I mean stay out of it)
  • deal is always just one step from robbery (and death)