Buying leather goods in New York is something many of us do either in a department store or from a street-side vendor, whose low, low price includes that nice feeling that you've probably been had. For a store that makes leather items its specialty, Il Bisonte (72 Thompson Street, 966-8773; and 22 East 65th Street, 717-4771) is the connoisseur's choice. Its made-in-Florence items include the jumbo carry-on satchel, script covers (director Ridley Scott gives them away at wrap parties), signature strap billfolds (secured by a strap of lingerie elastic), and legal-pad binders. Inventory is fastidiously arranged, and products are available in a wide range of colors, from very Milanese chocolate brown to eye-popping primaries.