…Buyers have shelled out lofty sums for the building. Nearly 70% of the residences have been sold, for an average price of $4,000 per square foot – a lofty sum not just for downtown New York but for all of Manhattan. By contrast, the average price per square foot of Manhattan luxury apartments sold in the second quarter of 2013 was $2,006, according to data compiled by Miller Samuel and Douglas Elliman. The average price per square foot for apartments in brand new development was $1,427. And when Houston Rockets owner Leslie Alexander snapped up the duplex penthouse last October, the $42 million sales price set a downtown record (dashed recently by 56 Leonard’s $47 million penthouse)…