Soilless mix is the most economical option and is also very effective. Ace Hardware carries Pro-Mix and the ones that don't will order it in for you. They carry both the small 1 cu ft loose bags and the large 3.8 cu ft bales. Be carful with the bales if you plan on carrying them a distance they weight about 60lb! You are going to have to provide nutrients though pretty much from the start though. Last 2 years I've been using Botanicare liquid nutes and FoxFarms time release. I am going to try to rely on the time release stuff even more this year I think. Hauling water just to feed is a major pain in the ass. You can add whatever you want to it really.
sodalite, I remember that raised bed in the picture from 2 seasons ago. Don't recall seeing how it worked out for you in the end I don't think. That was pretty badass I thought man.