I know your question is a week old now, but I wondered whether you had watched today's 1 o'clock BBC News. A young man from Portland was interviewed on his journey planned to go all the way around Britain's coast. He was doing this with sponsorship to help pay the �20,000 it had cost to rescue him from a boat he'd stolen a year or two ago.
Anyway, the interviewer said he'd covered 900 miles and still had over 5,000 to go. So, there's yet another figure for your consideration!