I travelled from Ajaccio to Bastia in March 2008, the fare was 21 euro. The line from Ajaccio to Corte is under major work so a bus takes you through the moutains to Corte then change to train to Bastia. The whole journey took 3 and half hours. By the end of April the train should do the whole trip. Ajaccio is 153 km from Bastia.
Ajaccio is on the west coast of Corsica, the trains lines go in like a Y shape across the island, to Corte, Bastia and Calvi. At this time [ march 2008 ] the tracks are being upgraded and new rolling stock arriving. The route goes through the lovely scenery of the Corsican mountains, well worth a trip even on part of the line.
I took the Corsica Ferry from Toulon mainland France to Ajaccio Corsica. The ship is modern and comfortable . The journey time was 6 hours but because of weather condions took an hour more. Tickets can be bought about up to two hours before departure at the ferry terminal. Bookings can also be done by telephone or internet.