When I was looking to purchase in Sioux falls SD I was using Katie clapper with Applause Reality.
Try Loopnet.com. Deals are usually not there, but brokers are. You can do a search based on the area and asset type they specialize in.
@Kim Heinrich your profile is sparse and there is no detail here on what you are trying to accomplish. It would help if you gave some detail on what type of properties you are looking for, where you are located and what your overall goals are. It is hard to recommend someone without knowing what you are trying to do. In my market "Multifamily" ranges from duplex that cost $100K up to apartment complexes that cost millions. You won't find one realtor that specializes in the full range (although they may say they do).
Thank you everyone. I am looking for multi family deals $100,000-$200,000. Working on the profile today.