Ferries to Kefalonia
During the season, ferries of "West Ferry" depart three times a day from Lefkada, while in the off-season, there are two departures only. The trip takes about 1 hour and 45 minutes. The ticket costs 8.5e for adults, and 4.3e for children. Children up to 5 years of age do not pay for a ticket. For shorter vehicles, the cost of transportation is 30 euros, and 40e for longer ones (> <4.25m). The schedule of departures can be seen on the carrier's website, here.
During the season, ferries sail from Kyllini on the Peloponnese to the port of Poros four times a day for about 1 hour and 20 minutes. You can see the departure schedule on the carrier's website, here. The ticket costs 9.8e for adults, and 5.4e for children aged 5-10 years, students and persons with disabilities. Transportation of vehicles is charged 38.7e. There is a discount of 20% for buying a return card.
Ferries from "Ionian Lines" company depart once or twice a day from Astakos to Sami at a price of 11e per person and 42e for cars. You can find more information on departures here.
Keep in mind that some ferry companies will ask you to make reservation before your travel.
If during your stay in Kefalonia you wish to visit Ithaca, you can use a ferry from Sami at a price of 4.8e for adults. Children aged 5-10 years, as well as students and people with disabilities, pay 50% of this price, and 17,8e is charged for vehicles. For more information about departures from Ithaca look here. More frequent departures and affordable prices from Sami to Ithaca are offered by Ionion Lines at 3e for passengers, and 17e for cars. You can find more information here. The trip from Sami to Ithaca lasts 30 minutes.