I bought a car once without it. (A BMW Z3M) and knew the guy from a forum. Flew to Tampa and visually looked at the car. Inside of the rear tires was down to the cord - was getting dark when I met him at airport and outside of the tires looked new. Vanos was shot, suspension shot and installed incorrectly which caused need for ~1200 in repairs and many small things that came up from someone that THOUGHT they were handy trying to fix and making them worse. Pictures all looked great.... person was well liked on bimmerforums. Was a mess.

The money for a PPI is a solid investment. The only time I would forego this is on a certified car from a well known dealer. Obviously that ship has sailed on any S2000.