There is a stand at the Union Square farmer's market that has them, but that won't help you today. Your best bet is trying Schaller & Weber or settling for paczki from Polish G.I. Delicatessen.
Union Square Greenmarket
Broadway and E 17th St, New York, NY 10003
Schaller & Weber
1654 2nd Ave, New York, NY 10028
109 1st Ave, New York, NY 10003
Oh wow, I can't believe I missed them at Union Square! Do you know if they are always there or if they were just there yesterday because of fat tuesday? I'm wondering if I could find them if I went tomorrow morning.
I will give Schaller & Weber a call this afternoon though. With a polish grandmother, I'm familiar with packzi too, but I think only a fastnacht is going to satisy today's craving!