[thstone]

I think that KBB is a good place to start, but typically there will need to be a manual adjustment for cars that are out of the ordinary (very low/high miles, specific equipment, receipts/no receipts, etc).

KBB pegs a 1999 Boxster with 15K miles at $10K. Upping the mileage to 75K miles drops the price to $7800.

Asking prices can be all over the map - someone can ask whatever they want, whether it makes sense or not. And some owners are willing to wait for years to get "their" price. To each their own.

In your case, I am pretty sure that the owner is asking well over the $10K KBB valuation and what you really want to know is how much more would be reasonable to pay and what would be the upper limit?

The problem with this is that it becomes subjective and everyone will have a different opinion. How badly do you want a super low miles car? Does this car have anything else that makes it unique or valuable to you?

If its just another used Boxster (albeit with very low miles), I would offer a little more than KBB, maybe $11,500, and then walk away if the owner wants more. There is no reason to overpay for a Boxster.