Notwithstanding that it's not in the TC metro area, the store in St. Cloud is Central Camera. Technically, it might be in Waite Park if you look for it's address. Not much of a used selection though, I wouldn't consider it for a special trip.
If you go to National Camera, ask to go up to the "Shutterbug dept". That's where most of the used large and medium format stuff is kept. National Camera keeps a good online inventory (www.ncepro.com).