I know there's a debate about what soil to use... I'd say just use what you can afford, but without added nutes. If you have good dirt in your yard, use it, but either bake it at 200 for a couple of hours to kill microorganisms/weed seeds, or solarize it. To solarize, you spread the dirt out like in a tupperwear tub or the like, and water it. Then, spread clear plastic over it, making sure it's about 2 inches away from the soil. Seal it up and let it set in the sun, all day, for like 3 or four days. The temps underneath will get high enough to do the same as an oven would. I learned this from a garden book because I'm using free compost this year for my garden and wanted to make sure it's kosher.
EDIT/ Solarizing can only be done in the appropriate season, like summer, when outside temps get high enough. I doubt if you could solarize successfully in winter.
Perhaps he doesn't want to take advice from a chic
