Some suppliers of radio parts:
Electron Tube Enterprises
Good prices and service
Antique Electronic Supply
Most well known source of antique radio supplies.
Zenith Parts and Radios:
Alan Jesperson, PO Box 17338, Minneapolis, MN 55417 - (612) 727-2489 fax:(612) 821-4821 - 8am-6pm Tuesday-Saturday
Most well known source of Zenith antique radio supplies. He is also the source for the Zenith Brochure Book. See his advertisements in ARC.
This section is slowly growing as I have time. Feel free to e-mail me any parts suppliers which you run across which deserves mention!