New York City market - investing in rental apartments

[Derek Melander]

Hi everyone,
I'm looking to purchase my first investment property (apartment in condo building) in either Manhattan or Brooklyn. I am just wondering what kind of GRM i should expect in such a competitive market? I have learned that in other areas of the country I should not purchase a property for a GRM of more than 8 but I'm sure in NYC I will not even come anywhere near that. My main goal here is to pick up a decent NYC apartment, rent it out, have an ROI around 10% and hold the property 20-30yrs. Would love to hear thoughts from experienced investors out there, especially those in NYC if possible.
Thanks,
Derek