Hi. The only decent place for inverts on Staten Island is Reef Fantasy. They have all the different snails in seperate tanks so you can see the difference of them. I would go with a few of all the different kinds of snails they have. that's just my opinion though.
if you can't find any good deals locally... i like the etropicals.com BYO clean up crew deal. Spend $60 and you get free overnight shipping. Prices are really good as well.