You can buy empty snail shells on Aquabid.com for a very cheap price. The shellies don't eat the body of the snail out of the shell in wild but find dead snail shells to live in. Snails are not apart of their diet. As hermit crab's shells are usually snail shells, go right ahead on getting those, but make sure the opening is at least 1 inch across. You can buy wild Shellies for $8-10, or tank raised shellies for right around $5.