Recent 996 buyer here (naturally aspirated, not turbo.)
Throughout the years, I've played the low/high mileage games with many cars. BMWs, Alfa Romeos, Toyotas, you name it. In the end, there are a few fundamental rules I abide by when looking for a car, despite mileage being high or low. For what it's worth, I had a very good experience with a high mileage E36 M3 and a poor experience with a low mileage Alfa Romeo Spider (then again...*insert joke here hahaha!)
Ask yourself or the seller the following and in no particular order:
1. How often is the car driven?
2. How often will
you drive the car? Or will it be a garage queen?
3. Service/maintenance records - does the seller have them?
4. Pre-purchase inspection - always pony up the few hundred bucks to do a proper one, along with a leak down and compression test.
5. Is there a reputable independent shop who knows these cars? If yes, befriend them and get their opinion.
6. How long do you plan on keeping the car for? Be realistic.
7. What's the local market like? See if there's any wiggle room to negotiate the final price.
I'm probably over-analyzing this, but this is just some food for thought. For me, it boils down to a bunch of variables. I purchased my 996 with 33,000 miles on the clock and given my age, financial situation, place in life, I could not be happier and I'm simply going to enjoy it as a daily driver.
Good luck!