Martin B. Retting's in Culver City. Just north of LAX. (It's really a gun shop, but they started carrying knives a few years ago. Good selection of production knives, and an impressively growing collection of customs.)
Ross Cutlery in the downtown LA area.
Recon-1 in Tarzana (San Fernando Valley area). Almost every production peice available. A few customs.
Your could visit Ernie Emerson's shop in Torrance (about half an hour south of LAX). Super nice people!
Strider Knives in San Marcos (San Diego area). Never been there, but I know people who have. Apparently very cool people!!!
Nordic Knives in Solvang (north of Santa Barbara). Be sure to pick up some pastries while you're there!
If you need specific info, e-mail me - I'll try to help you out!