Yes, hands down, it has to be Glenn Cohen's Scanners Unlimited in San Carlos. Note that he is currently "Closed For Vacation, Re-Opening Tuesday, July 18th"
Ham Radio Outlet, with stores in Oakland, Sunnyvale, Burbank, Anaheim, and San Diego is also worth checking out. While scanners aren't their primary products, they do have a good selection of stuff, and a couple of their people are "scannerheads."
I umm third that
Gln has EVRTHING a hobbyist or Profesional could need or want...
Scree Rat shack..
THe Caltrains and Samtrans goes through San Carlos
and its a small enough town to walk
SO NO excuses get out there and shop