The buzz phrase is "pocket listing". They are difficult to come by, one step beyond the difficulty of finding the guy that has it.
We searched for 4 years. For a couple of those years, we spent at least 2 - 3 weekends per month traveling up to 4 hours to walk another 20 or 30 or 40 ac parcel. Snow, rain, 2 feet of wet clay in a farm field. It was a real character builder. I loved it! I doubt that I will ever forget the first time I saw the pondsite basin of the LNP property that we ultimately purchased. It was that very moment that all those hundreds of acres we trudged paid out big. It is amazing the amount of strength and focus you generate when you can taste, smell, and feel the right parcel when you find it. It's addictive.