Concord is essentially right on the edge of "Silicon Valley" - try this list of surplus electronics places for starters:
http://www.junktronix.com/svss/
You might have to do some driving - but I would be willing to bet you'll find more than you can take back! Have fun!
BTW - check out their online stores first to get an idea of what places have, then give a call to them to make sure they are still in the same place and/or open for the public...