It's really not that bad. But its a pretty sucky airport, and you'll probably make up the $200 and then some in parking costs. Alternatively you could park at one of the nearby hotels and they'll have free buses going between the airport and the hotels.
You'll really love landing at JFK..... all the runways are too short, so they practically land on the water before getting to the airport, and have to actually pull up to get over the buildings on far rockaway right before they get there. You'll probably spend a good 10 minutes less than 25 feet above the water, close enough the plane actually gets turbulence from the waves, and yes, you can get seasick on a plane.
BTW, double check your Jetblue fare. They generally are not that great, they just look great initially because they list the price for a 1-way trip, while everyone else lists round trip.