At this point, you've seen a lot of information on gardening, and you're probably thinking something along the lines of "Dude, I can go to the grocery store cheaper!" You're probably correct in years 1-3 or so, but after that?
As with so many things, the big costs are up front. Plus you can bring costs down by spending some extra time on the garden. Don't complain, parking in front of the TV or computer is unhealthy. Get out there and sweat--it's good for you. :-)