Back in the good old days I bought a few Urchin licenses. It was fairly easy to setup and gave reports that you had to massage a bit to get the answers you needed. Urchin was purchased by Google in April of 2005 and was soon turned into Google Analytics. Google turned it into a free product (up to 5 million pageviews unless you have an active Google Adwords account, then it's unlimited pageviews).
I highly recommend this to anyone who needs to know where their visitors are coming from and how many visitors your actually have... in other words, everybody should have this installed on their website.
Website Analytics (Google Analytics):$0
Total cost of project to date: $59.99