Having a heck of a time tracking down updated info. Newer threads point back to this thread with a nice summary - but last updated in 2011.
Port Authority website now says only Terminal 1 has storage:
http://www.panynj.gov/faqs/airports....irportsJFKQu06
Regarding baggage storage, please contact your air carrier. There is one baggage storage location on-airport in
Terminal 1. Please call (718) 751-2947 between the hours of 7 a.m. and 11 p.m. for pricing and other specifics on storing baggage there.
I did call the phone number, they did answer and said it would be $11 / day for a 28 inch bag.
If anyone else has some recent experience with this, please post.