From craigslist:

12' X 12' X 10' Triangular platform with roof, 23' up in a tree.
Tree is located in secluded back yard used privatley by 1st fl. tenants.
E-mail for inquires.

Frankly, we could care less about this listing, even if it would be perfect for a lazy Daryl Hannah joke. No, we just wanted to go with the "grows in Brooklyn" line. It's a Gawker trademark, after all.

$150 - Tree House [Craigslist]
A List Grows in Brooklyn [PlanetGordon]