Blue Prints For A Salon Looking For A Collector Of Real Railroad Blue Prints Of Interlockings?

Looking for a collector of real railroad blue prints of interlockings? - blue prints for a salon

I have countless dishes railway interlocking real Pittsburgh PA area B & O, PRR, CSX, VOP, and railroads of local interest. I am interested to know what is worthless. Does anyone know of a collector or actions, the old maps from the 1980s are?