Not blockbusting but a similar technique

Blockbusting was how, post-integration, realtors would rile up a community to get white homeowners to sell once a black family moved in the neighborhood, and in turn would sell the houses to other black family, accelerating outmigration from the center city. (Blockbusting in Chicago, from the Encyclopedia of Chicago History; White flight, from Wikipedia)

This "notice" I found on my door the other week is likely a more modern version of the same kind of bottom feeding by real estate interests.