I spent £325 on a PPI when I bought my 993 targa from england recently. I looked at a few over here but I don't know what I'm doing and I thought shelling out such large amount of money without knowing what I was getting was too risky in the end. Got PPI from Peter Morgan who seems to be most respected, bought from 'specialist dealer', felt much better and safer about whole purchase. Even though the PPI missed some pretty major things (dodgy gearbox, targa roof leaking, warped discs) I'm still glad I had it done. In retrospect I'd probably buy from a better specialist and spend the PPI on warranty.
Either way unless you really know the type of car you're buying you'd be mad not to get either good warranty or PPI. I got a new clutch and few other things out of mine that would have cost me £k otherwise and this was a good car, if you buy one that hasn't been taken care of you could end up with a really really scary bill.
