Reply to Raing - try TheBikeMarket.co.uk It gives prices for most makes/models,and gives a year, dealer price/Private Price./ PX price all at a certain mileage. I allow £50 per 1000 miles to allow for the mileage above or below the miles given.
I find the prices stated, fairly accurate represent prices for bikes, that a lot of dealers are asking, but find that a lot of private sellers ask more than the private price stated.
The site is free to use.