Assuming you mean the Caputo flour for pizza, I just saw kilo bags at Garden of Eden the other day. Haven't been there in a while, but Buon Italia in the Chelsea Market might have it, too.They usually have several varieties of flour, anyway.
75 9th Ave, New York, NY 10011
Garden of Eden
7 E 14th St, New York, NY 10003
Just a quick update on this, I visited Garden of Eden on 14th Street today and they had none, nor did they seem to know what it was.
Found it at Buon Italia, in Chelsea Market though, two types, both by Molino Spadoni (Gran Mugnaio) both in 1Kg sizes, I bought both, just in case ;)
These are far in the rear of the shop on the right north wall...