I bought two swim diapers from Kelly's Closet - a Kushies for my daughter and a Bummis for my son. One of the main reasons I bought these wasy because I was tired of wasting about $10 for 11 disposables. I definitely need to put a swim diaper on my son whenever we are playing in any type of pool (I would chance it with my daughter since she is predictable), and I hate throwing away a diaper if it was only used for a few minutes.
Kushies - My daughter has dirtied hers three times. The terry insert looks nasty when I change her, but with a little washing (hand wash then machine), it comes out perfect. This diaper won't hold any liquid, which we discovered once when we were still getting ready to leave the hotel room for the pool. The only other draw back is the lack of laundry tabs. You have to attach the hook and loop pieces and invert the diaper to prevent damage to anything else you are washing with the diaper (including the diaper itself). But, I do like the tie in front - it is useful to help keep the diaper closed, especially over a swim suit.
Bummis - My son has yet to dirty his. It is a miracle or something because he is so unpredicatable. But, I think they would do well with that as well. These do hold water/liquid because the cover is PUL (or so I assume). So, when you get out of the pool, make sure to squeeze out any extra water before drying off (to prevent soaking a towel VERY quickly). I learned this the hard way today. I think ours holds more water than average ebcause it is a little big on him still (he is at the bottom of the size limit for a medium). Again, these don't have laundry tabs either, but that is the only thing I really don't like. Oh, and the pizzazz print has some pink in it. If I had it to do over, I would pick a different pattern.
Even if you aren't going to cd for real, I would recommend the resusable swim diapers. They are definitely cheaper, and work just as well (if not better) than disposables. And, since they aren't meant to absorb liquid, you don't have to be as careful about detergent.