In Manhattan, the vacancy rate is around 1.8%. That means there is almost nothing out there and what is there will have many people trying to get it. Bottom line, if there is no link or a link that goes not directly to the listing broker, the property is probably rented. Do yourself a favor and get with a broker.
Lastly, if you truly have the need to get this done, don't waste time by yourself. Brokers can line up whatever is out there and they may have something not yet available as well. Good luck.