Addison Homebrew Provisions is pretty good, and as stated Eric is an awesome guy. I havent been in a month now, so I dont know if it changed, but they have DME only! So if your a LME guy.... be warned.
Culver City has an amazing selection of grains, supplies, yeast ect.. But its an hour drive without traffic! But its probably the most complete store Ive been too.
There is also on in Long Beach that I went to once and I cant remember the name, but its close to the L.B. Airport. Stein Fillers?? I think, anyway they have great "kits" that I tried a while ago. I did a Belgian Double that was FANTASTIC!