Finding any water plants locally here is frustraiting. There is a small pet store about 45 minutes away that caters to the indoor pets more than outdoor ones, and on occasion, stocks small water hyacinth ($4 - $8 each) and water lily seeds. No nursery's local and only the big box stores about an hour away. They tend to carry everything but water plants. I've relied on purchasing water plants online. I try to find same State sellers to keep the "We can't ship this plant to your State" dilemma to a minimum. Using ebay's ability to see where the seller is helps with that.
I've had success with ones I've gotten from this site:
http://www.aaapondsupply.com. Purchased a couple of hearty lily's a few weeks ago and one has already popped up a couple of flowers. My lily's from last year haven't gotten that far yet. Flat 2 day shipping for all plants ordered helps.