Trapdoor Snails

I would love to have some trapdoor snails for my pond. Does anyone have some they'd be willing to share. I have lots of waterplants I could trade.
Or does anyone have a good place to order them from.
Thanks

I may, but here in PA we are all still frozen. It will be a month or more before I can check the activity of the snails. I'll have to wait and see. Last year, mine had a lot of babies, but I need to see if everybody made it through. What water plants do you have to share? If you DMail, I will keep it until the weather breaks. Then you can tell me at that time if you found some. They do a great job cleaning up.

Nnacy, Phoenix Tropicals has them sometimes.