I don't think you can buy a whole multi-story townhouse AND renovate it in any of those areas for $450,000 total. 11215, Park Slope, is the most expensive of the three zip codes--so, especially not in Park Slope.
Construction in New York City is really expensive compared with other parts of the USA. Your reno costs could easily be $400,000 for a whole townhouse. This is an easy area to get into money trouble with, so I hope you proceed with caution.
However, you can sign up for REO/lis pendens filing info from propertyshark.com and monitor what properties are available, and see what you think. Hard money loans are out there, as Barry suggests.
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