Why does knowledge have to cost so much?

Every Tuesday as I walk across university of Louisville campus I try my hardest to see only the beauty around me. I see the beautiful landscape but the buildings hold a painful memory for me. I know that even though I walk past these buildings every week the doors of almost all of them are closed to me.
You see a few months ago I had the foolish dream of sitting in on a class.  I assumed I would have to fill out an application or contact the professor whose class I wanted to take.  I never dreamed I would be asked to pay $1300 per class.  That is the same price as someone who is getting credit.  now I am reminded of my foolish dream every Tuesday.
There is a difference between education and knowledge.  I can understand why education has to cost so much but why must it be the same with knowledge.