The value of higher mileage Boxster's is almost entirely based on the expectation of how much longer the engine will last.
If you get another 65K miles out of the engine, then you got a great deal. If you only get 2K miles out of the car, it was a horrible deal. The impossible challenge is to know how long that engine will last.
Thus, at this time, we don't have any way to know if you actually got the deal of the century or if you made a $6100 mistake.
The best reason to buy a Boxster is that you love the ownership and driving experience.
And that driving experience is priceless.