Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Newark Airport to Kefalonia as you normally would.
Yes, there are multiple flights from Newark Airport to Kefalonia for under $900. The cheapest flight booked recently is on Multiple Airlines for just $891, but on average you can expect to pay $1,133.
The cheapest flight price from Newark Airport to Kefalonia is $1,454. On average you can expect to pay $2,302. The most popular route, (Newark - Argostoli Cephalonia), can usually be booked for $891.