Antique Radio Classified Magazine (
http://www.antiqueradio.com/index.html ) publishes a list of radio events, including swap meets, in the US and abroad. Here's the schedule through July and August:
http://www.antiqueradio.com/jun%20ju...g%20events.pdf
These are radio events, not TV-specific, but you often find at least a few televisions at a decent sized meet.
Phil Nelson