Cheapest I believe to have wide time scale so they can bring it on a return trip any time in next 3 months. Road transpost costs a little way down this BB, last 2 weeks.
Well 'scuse my scepticism, but why do you want to go from Palma to Barcelona? Unless they've moved it or my geography is totally wrong, Malaga's on mainland Spain, down near Gib, so the road journey is straight up the med coast through Spain, over the Pyrenees and then up through France. Where does Palma come into the equation? Only ferry journey is going to be Calais-Dover or somewhere else in France to somewhere UK. Or are you a doddery oldgit and want to go the scenic route;-)