Just to add my 2 cents i bought a mix of Nas and Periwinkle snails on the big auction, they were shipped to me dry and I plunked them into a container of tank water (a country crock one if i remember right). When they started to move around they got plunked into the main tank.
Just a note, all these snails, especially the periwinkles are insanely adept at aquarium escape. I put none in my fuge, but they have crawled on the outside of the siphon hose into the fuge, i pick them off the outside of the tank and off the J tube for my HOB filter frequently. I have picked a few of them out of the light hood but thats become more rare.
Just know what you're getting. Mine eat everything i put in the tank, so that's good for me