[Miguel Antonett]

Depending on what you're looking for. A 930 is a different machine, if in good shape there is no substitute; if a lemon = very expensive. Look for originality. Low milage is a plus; however, why the low milage - for real? Look for wheels alignment and height indicating wrecks or modifications. Look under the the car for wrinkles or bent pannels, gaps between pannels (i.e. doors to fenders to rocker to hood and bumpers; the gap must be pretty much the same all around. Paint color and shades of (repaint?). Have the drive train (at least) inspected by a Porsche mechanic.
Good luck!