Sorry, but because of the very high taxes in Nassau, you will not be able to find a cash positive deal with the numbers you mentioned. Your best bet is to look in Suffolk. You might be able to do better in the Mastic / Shirley area.

If you want to stick in Nassau, you might be better off trying to buy, repair and flip. With that, before you do so, you might want to read the following link:

http://www.propertyanswers.org/thread/135/Flipping-Houses-Can-I-Make-Money-.html