A site that specializes in Park & Fly rates at hotels is < http://www.parksleepfly.com>. For JFK, it shows the Ramada Plaza, on the airport grounds, offering a stay and 14 days of parking for $149. Booking through this site appears to require a stay at the start of the trip; if you're just planning a stay at the end of the trip, you might contact the hotel directly and see if you can arrange this.

Andrew Missouri