its probably the labour costs, rather than parts, we see prices closes to 100 bucks an hours from a back street garage that could probably just work out where in a boxster the engine is..
the there's the joy of having a spanner monkey work on your car that would probably have difficulty in spelling IMS, then he would probably revert to reading this forum for a 'how to' anyway.
oh how i yearn for the home garage workshops some of you guys have