The business of homelessness

Author's note:  I write this for my Dad who has told me I need to write this down, since the first time I asked it.

My first encounter with the homeless was in high school when I went to KC to serve soup at a soup kitchen.  My next encounter with the homeless was almost ten years later when I moved to KC.  I was working for the Area Agency on Aging and had to drive all over Johnson County, mostly taking the freeway.  As I pulled off and on the on and off ramps I saw homeless people.  Homeless people who were vets, homeless people who needed gas, homeless people who were out of work, homeless people who would work for food.  So this is the question I pose:  Where does a penniless person obtain a thick black marker? 
I have thought about this a lot, way, WAY too much actually.  Does one anticipate homelessness and take stock of all possible forms of weather proof writing utensils?  Do you panhandle by mouth and throw in a "oh, and I could really use a black marker, if you have one"?  Does a homeless shelter keep an old record bin with pre-written cardboard signs filed in some sort of 'by need' order?  If worst comes to worst, do you trade in one meals worth of money and just buy one to make the sign that will be your livelihood?
This also leads me to wonder about the network of homeless people.  Do you do any research before making your sign?  What gets the most money?  Should I go alone or take my baby?  Are other homeless people willing to share their secrets?
While I have no answers to these questions, I have decided to keep a stock of black sharpies in the glove box...just in case I come across a sign that says "anything helps. God bless".