I used to live at the beach and whenever I need a fix of surf culture, I head out to Val Surf. Located in North Hollywood, it's kind of a funny location for a surf shop, but I'm glad I found it.
This place has a great selection of boards and a knowledgeable staff that will help pro or novice find a good fit. If you are not a real surf Betty, but you just want to look the part they also stock lots of Zoo York and other beach-related gear to help you pose at the Pier.
You'll also find that since their overhead is lower in the valley, the prices here are significantly lower than other beachside surf shops.
Bottomline: Get your shorts and boards here, then head to Santa Monica for the surf.