If you're a fan of "old new york," you might get a kick out of the City's "tax lot photographs," which are now are now available for sale. For $80 total, you can have a black and white 8x10 of your building of choice taken around 1940 ($35) and a color 8x10 taken in the mid-80s ($45). There is also mention of being able to view low-res images of the Manhattan collection for free if you make a visit to the archives.
From the site:
Between 1939 and 1941, and again in the mid-1980s, the city photographed every house and building in the five boroughs. Photographic prints of these unique images are now available for purchase.
Link: Tax Lot Photographs
The Municipal Archives is located at:
31 Chambers Street, Room 103 · New York, NY 10007
Open to the public Monday through Thursday 9 AM to 4:30 PM, Friday 9 AM to 1 PM