It's by ferry I'm afraid - being an island we're a 'captive' audience!!!

I went on to the web this morning to check prices for that weekend and crossings (one way) ranged from £173 to £402. When booking a return trip the closer to the weekend either way the price goes up so out Thurs and back following Weds the total best price is £350. Go out Thurs last ferry and return last ferry Sunday, best price is £506... On top of that by using the late ferries you HAVE to book a cabin - cheapest is £37pp.
Then we've got fuel, acommodation etc.