It's approx 475 miles (estimated at 9 hours travel time)
Not having a car I've had to go on various websites re things like miles per gallon etc anf they may be out of date re petrol prices, but it looks like £100 each way.
It would certainly be do-able with a car - I've holidayed in Scotland before. But as an overnight trip it's a little pricey
ETA - just checked the trains
£106.00 return and only 7 hours journey time!
Hey Limey, any chance of a lift from the ferry?