I agree the price is high, but if you view it as three days camping which is included in the price it ain't that bad knowing how much our local campsites charge.
As I've said before they are trying to make a profit, but a lot of hard work and money has gone into organising it.
Even if you don't come up for Eroica Brittania, I can recommend the Peak District, and the the route is worth a ride around, even if I say so myself as a native.