I saw a very interesting chart today…

Source: http://www.riceconsulting.com/public_pdf/STBC-WM.pdf

If this doesn’t convince you of the value of unit tests, I don’t know what will. The cost to fix bugs in production could be dramatically higher than the cost to fix them in development, which is why having a suite of unit tests that you can run when you make changes is invaluable because it will prevent you from getting into these costly scenarios where you have to fix nasty bugs in production.