A friend has a piece of land in Manhattan he's interested in selling, best way to find an agent?

[Alex Madison]

He has an empty lot (you read that right, in Manhattan!) that he's owned for a while and he's interested in putting it on the market. Problem is, he's not in real estate and doesn't even know where to begin.

It's a pretty specific property, I mean it's really only available for an investor who wants (and can afford) to build on it. I work in Queens mainly, so I don't really know the Manhattan market of any agents at all. Anyone here have any experience selling commercial properties in NYC? Also, if he is to look for agents, is there any way he can try to narrow down agents with good track records who can help with a specific property like this? Any help would be greatly appreciated guys, thanks!