Chota has several styles of neoprene socks. I like the Gaiter Sock which has a scree collar that folds down over the top of your shoe. I have found this does a moderate job of keeping pebbles out of my shoes, especially once the socks are wet. I wear a polypropylene liner sock underneath to reduce friction with wet sandy feet, and to aid in getting the socks on and off. They cost about $24, and last fairly well. I have 3 seasons on this pair, but to be fair I alternate with 2 other pairs.
On a side note, I have recently been using Down Unders insoles rather then Superfeet. I find them to be more comfortable, durable, and a big plus, they are machine washable, and can be dried in the dryer on cool. They cost about $30, but IMHO are worth the extra 5-10$.
Matt