Keep in mind how pricing works on JetBlue.
Looking at a flight (not from BUF) it says:
Core Options from $244
But that doesn't mean your total cost will be $244.
If you click on it, you will see:
$244 for Blue Basic (free carry-on bag, no changes, fee to cancel, fee to select seats, last boarding groups so there might not be space in the overhead bin)
$269 for Blue (free carry-on bag, free seat selection, no fee to change/cancel)
$294 for Blue Extra (early boarding, expedited security if available, free change/cancel/same-day switches)
Even More $334 (extra legroom and a bundle of premium perks)
Free seat selection means they don't charge you to choose a seat, but all of the seats are not free. Some are, but others have an additional cost.
And there is a fee to check a bag.