What would you need them for?
I have the small Euplica snails in my tank. I received 2 adults from a friend shortly after setting up the tank; at first, they literally covered the tank walls with eggs, now I have many little ones, and they seem to establish a halfway stable population (less eggs on the tank walls).
Recently I received some Stomatellas with 2 frags, this was perhaps 3 weeks ago, and I see the first babies already.