Just came across this story where Tina Seelig at Stanford gave her student to make as much money as possible with $5 and 2 hours. It was a great story. Think out of the box and you might be surprised at the outcome.
http://www.psychologytoday.com/blog/creativityrulz/200908/the-5-challenge
She actually wrote the story in her book “What I wish I knew when I was 20”. I am reading it from my Kindle right now. It is a great read.
How much you can make with $5 and 2 hours