Alrighty, you want to be as close to main street as possible and don't go out past 16th street. I'd say within 4 blocks of Main and 11th is your best bet at finding something affordable. This however means you will live in a house. There are TONS of houses with rooms for rent. You should be looking at somewhere around 600 for your own room. 700 to be closer.
Next, your best bet is going to be with a skate shop rather than surf shop. A lot of the shops keep a pretty tight staff as in, they never leave. Jacks may be your best bet in that they are pretty huge and have a lot more than just surf. I'd say you would be better off just showing up with resumes in hand. Yes, resumes. People in California give resumes to work at starbucks. So make one.
Public transit down there isn't exactly awesome. So if you are in Huntington... youre pretty much staying there. It isn't an easily accessible area.
The surf isn't huge, but it is super consistent, hence the surf open taking place there and it being the surf capital.
If you are looking for the same lifestyle, but would like a bit more public transport action, like someone said before, Redondo/Manhattan Beach is just as wonderful. Best part is that it is serviced by the tram system. There is still a peer and a consistent break, it just isn't orange county and moving inland isn't so nice. But, rent you are expecting around $600 to be within a block or two to the beach.
Wish I could say that I still have contacts at any of the shops... but alas, they've all moved on to "careers."
Not kidding when I say this, go to www.mthigh.com and check out their forum. It is impressively active with just SoCal kids. A bunch of them live in orange county and are all super rad people. Just be honest with what you are trying to do and I'm sure you can find at least one person on there who manages or works at whatever shop.