Another angle might be looking for zoning changes, which typically are transacted by the owner, prior to the sale to a commercial company, who ends up doing the demos.
In my city, if someone owns a piece of property where things have grown up around it recently, and wants to "cash out". They would first apply to have the zoning changed from Residential to Commercial. At which point their property might triple in value. Then they can sell it as commercial property, with the structure being virtually worthless at this point. If the house is from the early 1900s, you got a great candidate.
My experience has shown that the owners are less concerned about the damage that you might do to their property/grass if they intend to sell it to a commercial company, who will just wipe the ground clean, lay down a layer of asphalt and build a 7-11.
Because the records for re-zoning are public, and at least where I live, are published prior to the zoning committee meetings every month, they would be a great resource.