Try Clubswim.com. They have a wide selection of suits and other equipment. Also, you might think about some aqua shoes for the pool. Running around on the bottom can be hard on your feet, really scrape them up. I have some shoes from this source as well, I bought the Club swim brand, and they are fine.
I have also bought from Land's End, and their things are great, very durable. They are more expensive but often have sales.
I have also noticed that some ladies wear exercise bras under their suits (I don't know how this feels, but they do it and seem happy with the result.)
I love to be in the water! And I'm always glad to hear of more people trying water exercise.