Foundation and raising are two different things. But if you want to raise it four feet above grade, you'll have to go at least four feet into the ground--maybe a lot more with widespread footings or pipe pilings since it's sand everywhere. I'm sorry I can't give local costs, only that it's likely to be prohibitively expensive for a lower end property. (My mother and grandmother were both from Long Beach and I was raised my first five years there in the 1940s. I've been back many times since. But I haven't built there, just tempted by sentiment.)

If you're set on doing it, check with a local architect, designer or engineer before putting in an offer.