With new sneakers hitting the streets every three months, the best place to keep up with the latest foot fetishes is Paragon Sports (867 Broadway, at 18th Street; 255-8036). While stores like the Sports Authority and Modell's (locations throughout the city) generally have lower prices and better clearance sales, they're no match for the breadth of styles and brand names in Paragon's basement shoe section (not to mention the hiking-boot room on the second floor). There's even space enough down there to take your favorite pair on an abbreviated test run. Just make sure to go on a weekday: Busy Saturdays and Sundays will frustrate even the most positive attitudes.