There are at least two CA Flea markets that are also worth mentioning.
For Silicon Valley there was the Foothill College Flea Market anchored by the then Electronics Museum located on the same campus. Due to circumstances forcing the Museum off the campus (a long story in itself) the event moved through a few locals to now reside at DeAnza College. The web bage is: http://www.electronicsfleamarket.com
The other BIG event that I'm familiar with (also an institution) is the TRW Swap Meet. The web page for that is http://www.w6trw.com/swapmeet/ and is sponsored by the W6TRW club.
This MIT flea market looks like a candy store for techies. I hope that the local kids who are learning and developing electronics know about it (and wish it had existed when I was a kid building circuits in Boston a long time ago).
IMO, things such as this are dying out for a variety of reasons, and there is no single cause. One of the reasons is our own "success" at making electronics so small and dense that you can't do anything else with the parts, assumoing you can even get at them.
I think the golden age of flea markets was in the era of discrete transistor and small-scale ICs (DIP), when you could build circuits on perfboard or similar, and poke, probe, change components, and "mess around".
Now the best thing to look for when at flea markets are power supplies, and also electromechanical components such as connectors, or motors for robotics.
As we unveil EE Times’ 2015 Silicon 60 list, journalist & Silicon 60 researcher Peter Clarke hosts a conversation on startups in the electronics industry. Panelists Dan Armbrust (investment firm Silicon Catalyst), Andrew Kau (venture capital firm Walden International), and Stan Boland (successful serial entrepreneur, former CEO of Neul, Icera) join in the live debate.