Where to buy land snails/escargot in NYC
Do you want live snails? I don't think they are available except for the ocean variety - perry-winkles.
Cleaning land snail, if you could find them, is a long and, frankly, stomach churning process that involves allot of purging.
Therefor most restaurants use canned snails, the superior ones being from Burgundy, the cheaper and smaller ones are from Indonesia. The Helix brand (French) are very good, but any French brand should do well. I imagine all the gourmet markets from Grace's on the UES to Fairway carries them.