[mikefocke]

You'd know about the condition of most of those items and the O2 sensors are only ~$240 a pair.

I owned 2 Boxsters over 6 years, each bought at about the 6 year old mark, each as the third owner.

I spent around $0 on my first one (totaled it).

My second I spent:
$1500 in normal maintenance I knew it needed when I bought it because of a PPI and the price I paid for the car reflected that cost (alignment, brakes, 60k service).
$75 to replace 4 tires/wheels (yes, that is right, I bought used Michelin Ribs from a dealer as take-offs and sold mine as used...lucky)
$500 in repairs (2 sensors, seat belt/airbag light)
$1050 in tires (due to age, not wear out)

I don't count normal oil change and the like maintenance.

So while I agree that you should always have a reserve cushion, owning a Boxster can be a very economical experience too.