Good luck! I have spent all last week looking for water/beach shoes! I waited too long, too. We are cruising in Oct. and I kept waiting for the shoes to go on clearance. Well, all the stores are running out, and they're still not on clearance! K-Mart did have them buy one, get one half price. They were $5.99 for the first, $2.99 for the second. But they had very few sizes left. I only found my husband's size there, not mine.
I found some at Wal-mart, only about 20 pair total left, mostly children. They had my size, but I hated them, they hurt my feet the second I put them on. They were $4.99 (I think). I was told by both stores that all the ones they had left were out.
I am not a swimmer and don't plan to snorkle, but my husband might. I have a pair of Teva's and a pair of Ocean Pacific Teva-like sandals that are the black rubber soles with waterproof straps. I've decided to just use them. If I decide to wade into the water (which is about all I will do) I'll just wear them in. If you really want to swim, this probably wouldn't work, though.
BTW, Wal-mart didn't even have their bathing suits on clearance yet!