Unlike many other parts of Michigan and the eastern US in general, the sale of personal property from estates in Ann Arbor is most often done with Estate tag sales. These are typically announced in the Ann Arbor News classified section, and are generally managed by a cabal of professional sale organizers.
Because Ann Arbor has been a college town for a long time, many of the interesting tag sales are personal property of interesting old professors. You can often find books, fine and decorative art, ethnographic collections, and other special items. You won't find those at Garage sales, generally. But the price at tag sales is generally fixed for most of the day, so don't expect to purchase at deep discounts you might see at Auctions.
Note: If you arrive before opening, you'll line up in front of the venue in order of arrival. If the crowd is large and the venue small, the organizer may pass out numbers to the line, and allow only the first 20 or 50 people in at time.