That's about where I'd make my offer. Might be willing to move up a couple hundred from there if everything else checked out OK, for no reason other than that my time and the effort of driving all over the southland looking at bikes costs something too.After looking at it and running it, I'd offer him $3K and tell him it's because of the high mileage and the fact that if you do the same as him in the next 3 years it'll be 80K miles and you'll really struggle selling it for much, not to mention the amount of service it will require in the next couple of years. If he says "No", leave him your number and tell him to call you if he changes his mind. Chances are he's not going to sell it for more than $3500, and if you keep an eye on it, he'll probably come down significantly if he really needs to sell it.
The key is to not be sold on it when you look at it, act concerned about the high mileage, and make that obvious to him. Be willing to walk away.