In addition to the above suggestions, you might see if management companies like SL Green have internal buyers or purchasers you could contact. Hotels generally have people who do this; the largest management companies might also. Crain's New York publishes a number of lists with business contact information--I believe one of those lists covers the largest real estate management companies in the City.
I'd skip commercial galleries because they would require jumping through all the same hoops as if you were looking for exhibition opportunities or representation--because you would be.
I've not looked for this kind of opportunity myself, so take the above with the proverbial grain of salt. If you're in the City, I'd be happy to grab coffee and see if any of the interior designers or architects in my network of contacts might be useful for you.
-m