I bought my 2000 S just at 130k miles last August. Now has over 140k. I changed my own oil at 10k miles and the filter was very clean.
It's been bliss with some minor repairs. Don't let some folks here scare you about the 'unknown' history of your car. Drive it and love it.
You can afford to at the bargain price you picked it up.
edit: I'd like to add that I bought the first boxster I drove in my price range, without a PPI.
It's just a car.