Just for cost comparison / reference - since TT23 i've been to Muse gig at MK Bowl and F1 Free Practice Friday at Silverstone ... at Muse one 330ml can of beer was £6, soft drinks £3, chips and various average chicken £14, very average pizza £14 and £90 ticket booked well in advance to see 2 & 1/2hrs of main concert ... F1 Friday the ticket was thankfully free but retail was £140 - no seating or parking just general foot admission, very small portion fish n chips £15, very small portion chips £5, 500ml soft drink £4 ??? and very small (half size of Davisons IoM) ice cream £4 .... all way more than anywhere at TT or MGP but just checked boat for car+1 mid / late August and it's £470 to get on the boat which as has been mentioned is a huge amount of money before any accommodation has been paid for.