I'm sorry for the late response. You asked this question about 20 days ago, which means you probably have already found a place. In any case, I don't know if you can find any apartment in Harlem under 1K, and if you can, I don't know if you want to live there. I know the building where I moved in when they only were charging under $1k a month has since raised their prices up. Now apartments there start at $1,300 a month. Still, if you want to find something spacious and affordable go further uptown to Washington Heights. There are places that have a lot of room and are affordable. You just have to be willing to venture out a little bit.