I thought that the top price seat on JetBlue was $202 (with taxes, etc.) I am flying JetBlue the day before Thanksgiving until November 30th, and am paying $289 RT from NY to FL, which was about $100 LESS than other airlines.
In any event, JetBlue considers themselves a Premium Economy airlines, so their fares generally run higher. I've heard their seats are roomier, and they have better service (a TV at every seat is constantly mentioned). I've never flown them before, so its hard to say.
Exactly what dates are you flying? Is it close to Easter or Passover?
Donna