It is most definately worth hunting for mint & unmodified originals. They only ever made 500 Storms, so they are getting pretty few and far between.
Expect to pay anything from £7,000 to £9,000 for a very good condition one - and make you sure you look for the specific Storm features (as lots of people try and sell VR6's as Storms, when in fact they are not). Storms should have as standard :
* Red 'Storm' badging on rear of car
* Red 'Storm' badging on centre console
* Solitude six spoke alloy wheels
* Leather interior (cream on Classic Green and black on Mystic Blue)
* Should be either 'Mystic Blue' or 'Classic Green' colour.
Good luck.. and don't rush. Plenty of people have ruined Corrado's by missing services and just thrashing the arse off em..