I looked into this a year ago. You're right: "dry-aged beef" is the fancy expensive stuff your yuppie butcher is selling you. "Wet-aged" is everything else -- they pretty much stick it in a plastic bag in a brine that breaks down tissue. If you don't do anything what you have is a curiously tough meat product.

Wet aging is cheaper because you raise the water content (and thus the weight) a little, whereas in dry aging you lose a bunch of moisture, and because it only takes a week or so.