acox914, I Think I can answer a few questions..
hp? the one on ebay is 450, but there were many different varieties of engines, those things where FAST....
I think there were 50 made, dont know the exact number though.. but not many.
I think they made them from 86 to 88... dont quite remember
Why are they expensive? Porsche put all their technology into those cars, Soooooo much technology for that time.. Then they used that technology in that car and all the following cars, like for example, their 4 wheel drive.. Look at all the other cars that where on the market.. look at what they had, then look at the 959, its advanced.. still is.
BTW Vortex, cant see your pic..
but here it is the link
http://erntheburn.tripod.com/autos/959/pors12.jpg