Intersection of 57th Street and Fifth Avenue.$1,500 per square foot.Wall Street may be melting down a few miles south, but rents on New York's prime retail corridor, Fifth Avenue between 50th and 58th streets, hit a record high this year. With that kind of overhead, some retailers tend to view their stores here as expensive billboards instead of merchandise movers. But others, helped by a crush of European tourists, are raking it in: Tiffany's Fifth Avenue flagship saw sales of $7,500 per gross square foot last year, 10% of the company's total revenue.