From last year's thread (unfortunately posted after the event, as I didn't realise until after).
You can buy a groupsave to Ryde, including the ferry, for £165. This is £41 return each for 4 and this is cheapest unless you book trains way in advance. Also gives you flexibility as you don't have to travel on particular trains or ferries.
From last year's thread (unfortunately posted after the event, as I didn't realise until after).
Also avoids this outrageous new booking charge.