Those looking to buy Montauk's "iconic" Shagwong restaurant and tavern should probably pursue a deal through Brown Harris Stevens and not Atlantic Beach Realty. Why? The BHS listing is a full $750K cheaper. Tony Cercio's got the place going for $3.25M (down from a high of $6M), while Lisa Grenci just listed it for $4M. Why the price differential? No clue, but we expect a flurry of tersely worded Emails will be exchanged this morning.