You have the right idea, but i think buying the amount you need by the bag, would be expensive. Check for landscape suppliers where you live and see about buying topsoil by the yard. This will be a mix containing compost as well as soil. Al

What is your elevation a block from the beach?

I used to live on one of the islands in Huntington Harbor. I had two problems growing things. One was the very sandy soil. The other was that the roots would hit salty soil once they went down 6" or so.

New grass would be fine until it gradually built up salts since the salts wouldn't wash down into more salty soil. Removing and replacing it with new sod worked well for 5-10 years but trying to re-seed was pointless, at least with the commonly available types of grass.

I managed to get some citrus to do well by building a pot for them in the form of a 18" raised planter. Those trees did well until they reached about 15' tall and wide. They were removed in a remodel by new owners. My ficus elastica did fine in the natural soil. It is now about 30' tall and wide. How about finding plants that tolerate the salts well?

Lots of water. I find that heavily composted sandy soil drains in a day or two, so I have to water my veggie beds every day or every other day. You might want to check that. I added regular topsoil to my beds.

Otherwise, I agree with Al. You can get plain old topsoil to fill your raised beds, and build them high, to avoid Greg's problem.